Even if K1 was 100x more powerful than 780Ti, Shield had 4K screen, and you could stream every single 3rd person shooter at 4K with 0 lag, there are 3 aspects that can't be overcome - controls, screen size and usability.
Shield tablet is not a dedicated game console, it is just a really good tablet with stylus and with an optional gaming accessory and a mini HDMI output so that it can be hooked up to the big screen TV if desired.
You are going to buy a $40 stand or use a book to hold the tablet on the table?
The $39 accessory is a smart cover and multi-position stand for the tablet. Most people who buy a tablet (iPad included) will want a smart cover for obvious reasons which have nothing to do with gaming!
For about 2 hours you salivate that you have the worlds most powerful gaming tablet and then you realize the screens on the Samsung and iPads blow it away in real estate size and resolution.
Again, have some perspective. This is not a dedicated gaming tablet. This is a really fast Full HD 8" Android tablet with stylus that sells for $299. Obviously one can always spend more to get a larger tablet and/or even higher res screen, but so what? A higher res screen is not always a good thing, because platform power consumption is higher (all else equal) and graphics fluidity at native resolution is worse (all else equal). And not everyone wants a 10" tablet. Most consumers appear to be content with a 7" or 8" tablet.
Take a step back and think about things. For $299 I can get a high res Full HD pure Android tablet with 8" screen, an integrated magnesium thermal shield for superior heat dissipation, a
stylus, a microSD card slot (up to 128GB expandable storage), front-firing stereo speakers, and one of the fastest ultra mobile SoC's on the planet in Tegra K1 (with
2x better CPU performance and
3x better graphics performance than the Nexus 7 2013!). All the gaming features aside (which are entirely optional in the first place), this is a very fair price for a tablet with these features and specifications.