Thats so not true. If it was true than there was no multigenre engines like CryEngine, Unreal Engine or Frostbite. Tech features can be used for art purposes, but its not like people create only specific tech just for specific art in engines.
And yes, You can and You should seperate art from tech, because its totally subjective. Its like You would said that Crysis 2 isnt look amazing, because its art isnt that great or decrease importance of its tech, because art is not up to pair, right?
What are you even saying here?!? "Tech features can be used for art purposes, but its not like people create only specific tech just for specific art in engines"... huh?
Graphical features in an engine like: texture filtering, anti-aliasing, ambient occlusion, radiosity, sub surface scattering, parallax occlusion mapping etc etc etc were all invented to take game art and try to visualise it in a way that makes it look clear, believable and realistic. Graphics technology doesn't exist without art, because its the art that the technology works on to create the image that you see on screen. Do you even know what you are talking about because it certainly doesn't sound like you do?
Also, almost every graphical technological engine feature can be implemented in a game to varying degrees of quality. Take a look at AA for example, you have MSAA, MLAA, FXAA, SSAA and a whole host of other more exotic implementations as well as combinations of different techniques. Just saying this game has "X" feature is meaningless because a game like Crysis can use a more performance demanding feature like their "realtime" GI approximation, and yet a game with a much cheaper to implement baked lighting solution can display vastly more impressive results.
Killzone games for example don't use HDR lighting, and yet the lighting in those games outshine a great plethora of other titles that spend copious GPU cycles computing high quality HDR lighting.
Every games on a fixed platform makes compromises in terms of what graphical features it includes and it doesn't, as well as to what quality of the implemented features is used. Thus its just straight up ignorant to compare games solely on the list of graphical techniques that are used, and completely ignoring everything else.
What does it even means 'as polished or high quality' when all Your mentioned games, look far from excellent or even great in most situations. I can post dozen of screenshots from those all games that look bad or even atrocious.
Well at least you're asking questions now, which is really what you should be doing to learn more about the subject matter of which you are clearly not an authority, despite the way you ty to present yourself with your posts. See above for the answer.
As for the rest of your post, you're very much entilted to hold such an opinion about those game, despite your opinion being objectively an unpopular one amongst the masses. The prevailing mindshare however would disagree with you, and so would I as luck would have it.