I wouldn’t say anyone is “forcing” anyone. Just that’s how they’re doing it.
IMHO if you’re concerned about tag (and class) bloat, WordPress isn’t for you.
Sure, it can be nice to have a lot of things to use in styling, but most go unused and only add confusion.
Applying effects to other elements doesn’t always achieve the desired effects in every browser. Divs on the other hand usually do. AFAIK, using containers is considered good practice even if you can achieve the effect through some other way. That’s the way I do it and I’ll continue to do it until I’m proven wrong for some reason or better methods are developed.
<center> is deprecated. You should not use that anywhere.
This tag has been deprecated in HTML 4 (and XHTML 1) in favor of the CSS text-align property, which can be applied to the <div> element or to an individual <p>.