I hope someone starts force-updating your terminal and editor/IDE, introducing all sorts of random changes. Maybe then you would understand why it is bad to make your users' lives worse to make your own life marginally easier.
More seriously, I have a software setup that I have configured to be secure and useful. Switching to a newer version of $whatever might help or hurt in either category, but it's a change I want to make deliberately. I don't see why changes preferred by $randomBrowserVendor or $adCompany will automatically be in my interest.
I disagree with the sentiment that somehow using new features is obligatory and directly related with how much "better" a website is; in fact the most informative and most visited sites I use, are also the ones that tend to be the oldest and not use any of these new features- often hand-written HTML4 or even 3.2.
You've got to be joking? Even if it's true that you mostly use websites that don't make use of new features, then you are extremely unrepresentative. Anyway, even simple content-driven sites like Wikipedia make use of a lot of HTML5 stuff now in ways that aren't necessarily obvious to users. And although much of that stuff could theoretically be made to work in older browsers, it's not viable to do that because it would be prohibitively expensive to maintain. So not as much good stuff could get built. That's how end users benefit.
But the real problem is this:
> in fact the most informative and most visited sites I use
You are mistaking yourself for the majority. Therefore, the reality is, none of the above will be "better" as defined by you. However, if what you are saying is true, then any site of yours using HTML 3.2 would be a better site as a result of using HTML5, as it's more semantic in nature, and as a result, provides better support for providing usability and accessibility.
You are free to disagree, of course, but you'd be wrong because your reasons are not 'better' than mine.