A CLC cooled card combines both the strengths of the blower, and the open air cooler.
It exhausts hot air outside the case, and as a bonus the rad can be mounted on the back of the case to double up as the exhaust fan, usually the top 120mm in the back... and has not only the temperatures of a decent open air cooler (see the Tri-X and Vapor-X coolers from Sapphire) but also the low noise level they have, too.
To even think that a CLC cooled card is inferior to one with a blower or an open air cooler is insane, there's no logic in that statement!
Nobody is debating that a CLC cooler is inferior on the grand scheme of things. In fact, from what I gather, everyone agrees it would be an awesome option.
Key word: option. As crazy as it may seem to some of the extreme techies here, a CLC is not the answer for every enthusiast, and is especially not the answer for the majority of the public. True, some of both categories will buy such, because of all the reasons they are so well received: great at cooling, typically less noise, and perform double function so overall less fans in the case and less noise altogether.
But that does not make it the one cooler to rule them all. Plenty of people either cannot host such coolers, or do not want to deal with them. "Deal with them" you ask? Well, everyone has their own personal reasons for whatever they do in a PC case. I'm not making excuses up, that's simply the sentiment of people. Some want these things, some want the standard simplicity of air cooling.
One chief reason I can cite for people choosing air over CLC, even when their case and build decisions make it a possibility without sacrifice: they don't want water, period.
These systems are not fail proof. Are there warranties? Sure. Is failure exceptionally rare? Basically. But water leaking is also not the only failure. These things WILL need topped up with water if you keep it long enough, they are not perfect barriers to evaporation that happens in all cooling systems with time. Maybe you won't keep any single CLC package long enough for that to be an issue, but for some, it may very well be a concern.
Next up as a concern, other failure issues. The pump can fail entirely, which renders the entire system down until you can replace the entire CLC package. With an ordinary fan, you simply replace the fan, and quite likely, thanks to the heatsink, you can probably keep on trucking at 2D base clocks until you replace it. Without the pump, that GPU isn't getting any cooling accomplished, period. It will be down for the count.
Another concern, if not for pump failure, you have abnormal pump noise. I have seen it reported that pump noise has been a nasty detractor from these CLC packages. Not necessarily common, in fact, it must be fairly uncommon considering the overall reviews, but it is common enough that it is reported in the forum communities like overclock.net.
There are enough issues that simply do not exist with air cooling setups, enough that make it not a walk off homerun when it comes to cooling. It is, quite matter of factly, not for everyone.
To reiterate, for some, they simply cannot use the system without making drastic changes. Many PC gamers or other rig builders do not necessarily many any build decisions with the idea of adding any kind of water cooling setup later on. Others simply do not want any kind of CLC or other water kits for fear of the potential of damage, or of the other inconveniences. Even if failure isn't with the CLC kit itself, a failed GPU (especially third-party CLC on a normal GPU) or a failed CPU means more inconvenience diagnosing the issue than standard air or even factory kit setups. For most enthusiasts who go this route, true, that isn't an issue due to overall knowledge, but not everyone wants extra hassle. Regardless of how anyone argues, it is an added hassle that does not exist in other setups. Minor to some, crossing the line for others.
Many here take part in true water cooling setups, and from what I've seen, some seem to be entirely biased to the point that it seems they feel superior and everyone should aspire to emulate their success. Water cooling is simply not what the average enthusiast wants to deal with. The water cooling route is exceptionally rare when you really boil down the numbers.
CLC kits are, however, gaining acceptance in all the computing crowds, so yes, people do want it. I make no argument to the contrary. I simply argue that not everyone wants it.
And ultimately, the "detractors" in this very thread have not argued for the mass ban of such cooling. They simply took to crying foul with the idea of the cooler being the reference cooler. Reference coolers are very popular when they are successful. When they suck, the aftermarket comes to the rescue. If the card maintains the same TDP as the current flagships, then AIBs COULD make custom coolers, but one might have to argue, how strong will the appeal be? And how well will they truly compete with the reference cooler if it is a CLC kit?
If there are indeed options, and good options, everyone will be happy. Again, no one has actually suggested otherwise. Some have made no mention of "well, if there are options...", and simply complained about the *rumored* reference cooler, myself included. Take this to simply be arguing that the reference will be likely the most efficient and effective cooler design, because it most surely will, and due to that, we fear what the AIB partners will do. Everyone assumes they will make other coolers, and everyone assumes the stated TDP figures and other facts are accurate because they are on charts. Nobody truly knows for sure, so we are all holding our breath, and thus, simply voicing our hopes that options remain available for everyone when it does come time to launch.
This isn't a matter of "well this is AMD's solution... ehh, it's not good until Nvidia does it!"... no, just no. Stop. It's childish, and embarrassing. People just want options, and don't want to be forced into a solution that may not work in their case, or introduces more risks or the potential for more issues than which they are comfortable accepting.
FWIW, I also question the wisdom of placing radiator coolers as side panel exhaust and/or even front panel exhaust. Perhaps they desire negative pressure cooling, and perhaps they are even comfortable cleaning out their case more often. What that doesn't address is how much of a change that is to the standard airflow that the ATX standard is really built around, and how most PC cases are designed to accommodate. I thought about doing that myself, but it doesn't seem like it would be a good airflow solution. Every actual test I've seen of airflow and temperature modeling within PC cases demonstrates the best temperatures with the standard airflow model, with one possible variation: first, the standard includes a possible mix of front, bottom, and side intake, with possible top and rear exhausts; one variation I have seen measured with good result is, at least in some PC case designs, the top is turned into an intake, all others remain the same.
Shaking up the airflow, without careful planning, can introduce deadzones and turbulence that, in the end, results in less optimal cooling for random components, dependent upon the actual airflow situation. And perhaps the front panel is the only solution for some cases: in almost every example I've seen, that requires removing all of the drive cages, or one if it's a half and half cage assembly design, and that may not leave enough expansion potential depending upon the user and their storage preferences or requirements. Going with extensive 3.5" RAID, an optical drive, and additional SSD system drive(s) requires a fair bit of mounting space, which may very well render the idea of putting radiators in front an impossible option.
I speak from some personal hesitation and issues, as well as common concerns I've seen repeated on OCN.
TLDR:
not everyone wants the risks and potential issues associated with CLCs
not everyone can even host CLCs
we all simply wish that there are options, and not a required CLC;
additionally, the fear is that a reference CLC equals the best and most optimal solution, so how many AIBs will make other designs, and will they sell enough to justify continued expansion of non-reference designs. Will they even be sufficiently overclocked/overclockable compared to what the reference design can achieve?