Whenever I want to check up on proposals I'm following on Area51, I have to go to Area51, go to my user page by clicking my profile icon at the top of the screen, switch to the "Info" tab, and then scroll down to find proposals I'm following / committed to. It's not too much work, but it seems like more work than necessary for the most frequent thing you'll do on Area51 (check up on proposals you're interested in). It'd be nice if there was a "Participating" button on the sidebar for a quick way to get a breif overview of all of the proposals you were following, because, to my knowledge, the next quickest way to do that is to visit the Info section of your profile.
I think that would turn out to be logically inconsistent with the way any other site works. If you want to see your own content, you go to your profile.
You are picking out a very specific preference and asking to make a button for it. But if someone else wants to see their favorite questions (for example), or their own questions (for example), or their latest activity (for example), we would be sprinkling profile stuff all over the main page.
If you want to go to a particular page more often than most, I would suggest bookmarking the page and saving it in your browser… or dropping it on the tool bar or even right on your desktop. That way we can let everyone customize the experience for themselves rather than cluttering up the main page with a lot of links already organized elsewhere.
That's just my opinion: The current setup seems more organized, flexible , and logical than bringing bits and pieces of the profile out to the main page.