I think the problem is that the case designers and people like the ones in this thread have two different viewpoints and there's a disconnect. This "restricted airflow" is only a problem if you make it a problem. They've been making servers who's front panels are completely filled with drives for years now but manage to keep not only a dozen hot drives sufficiently cooled, but two processors with small-ish heatsinks, a buttload of RAM, etc. This is where the disconnect comes in. It's not that you can't get enough airflow through these case designs. It that you don't want your computer loud enough to do it.
While it's understandable that nobody wants something that sounds like a vacuum under their desk, I think people have gotten a little carried away with trying to completely silence their PC's. Even if my computer was silent, I've still got a ceiling fan that squeaks, neighbors cats who love to mate in my yard, kids with fart cans on their cars, etc. At no point in time is my room going to be silent and if it was, that would honestly be more distracting at this point than some background noise. You need to find a balance between noise and cooling capacity. Can I hear any of my computers over the speakers I'm using? No? Then mission accomplished in my book.