Developers now are not trying to push boundaries in technical depertmant they're trying to stabalize technology and focus on making things more playable and less buggy this time around with less focus on making "BETTER GRAPHICS!!"
Sorry, but that's just wishful thinking. As long as people keep choosing the better looking game when placed side by side, and reviewers give buggy games a pass in favor of amazing spectacles, devs will keep doing as they have been doing. So far day 1 patches are going no where, as well as games released with bugs.
Anyway spending less time on optimizing and making better graphics is in no means a guarantee that the gameplay will be better or there will be less bugs. There are plenty cutting edge games without bugs and good gameplay, as well as very basic looking games with bad gameplay and game breaking bugs. It's different teams that make the engine, artwork, gameplay, and do quality assurance.
Having the same architecture all around, easier hardware to work with and better dev tools will definitely help with the bugs and stability. Still in no menas a guarantee that this gen won't produce a ps3 like Skyrim.
Mobile and Indie games are always popular to drag into the gameplay over graphics debate. However over 90% of them are crap. Most of the remainder are 1 trick ponies, that usually become repetitive / boring after an hour, or are only interesting to a small niche. And ofcourse it is easier to make a bug free decent performing indie game with simple game mechanics than a complex 60+ hour open world rpg.







