I think the right-hand sidebar is mostly ads, guys. I'm guessing that in order to keep SR running (paying for tech staff, employees, website hosting fees, server space, etc) that they elected to support some advertising. It's been minimal in the past, but I'm thinking it's more visible now because there were bills to pay. This isn't just a reddit thread, running SR is a full-time job for a handful of people. They developed an app, and have probably hired new people because of the growing success of the community.
I know everyone HATES new technology. But this is the Internet, after all - a place where things change quickly and tech-savvy users make adjustments. I'm sure by next weekend we won't even notice the sidebar. Heck, I didn't even notice until I saw the negative posts today when I just logged in! In short...we'll live. C'mon guys, get positive!