SEO becomes obsolete?

Well, many criticize SEO because it doesn't really address quality of website (informative website, etc.). That's what I brought it up ...

Ok, I think I understand where you're coming from on this. Are you referring to the idea that higher quality sites should rank higher in the SERPs but don't because some lower quality sites are gaming the search engines through SEO?

I believe so. Not in all cases, but this happens quite often.

IMO, some of the responsiblity for poor search results falls in the hands of the webmasters. Algorithm's are built for Information retrieval not mind reading. I'm confident you will agree that an overwhelming number of web pages on the the Internet are poorly structured and/or optimized. I imagine the webmasters of these pages are among the many who are not happy with the SERPs.