I have seen many stack exchange sites have modified their user-page and started using the new user-page. Why EE.SE isn't?
I believe it's going to be rolled out to all sites and the only reason the release has been staggered is because of changes needed to upgrade the CSS style sheets. There's a summary here of which sites have been done already and which are planned and that includes EE.SE:
If you look at the revision history you'll see progress on the remaining sites is slow but steady, but I'd expect it to be completed within 6-8 weeks.