But it's not a completely new version and calling it 3.0 is mispresentative.
2.1's theme is an evolution on top of 2.0's, so much so that it is literally called 'Curve 2'. I also suspect that someone will remake the 2.0 theme for 2.1 with all the goodies and shiny things like much improved mobile support (like 2.1 already has out of the box and that 2.0 can't do with its current theme)
2.1 is also built directly on top of 2.0, in a way that a 3.0 wouldn't be.
Though I find it interesting that the look is the only comment, and not any of the new features, like draft posting, or alerts, or new CAPTCHA to improve registration or... but that your only observation is how it doesn't look like something that was designed 10 years ago and was already out of date when it did finally appear in the first place.