As with most social media, what you get out of Twitter is largely a function of who you follow. Using it as a "direct connection from people of note" is using it exactly wrong IMO. That makes it just another megaphone for advertisers, politicians, and entertainers. Personally I find it much better to follow people whose ideas and perspective I already find valuable. Some I know IRL. Some I know from their work, or from blogs/forums including this one. Some I was "introduced to" by these others, in the sense of repeatedly seeing retweets or responses and finding them valuable.

I can get the news a bazillion different ways. I don't need Twitter for that. But I also enjoy seeing the reaction from the various communities of which I'm a part, from work to the ski club to the people I follow on Twitter or Facebook. Social media is much better when it's social, not broadcast.

Am I in danger of creating my own little bubble this way? Sure, as has always been the case with RL associations as well, and the remedy is the same as well - learn critical thinking, don't rely on any one of them for your information, etc. And even if each of my social-media "avatars" is in a bubble at least it's my bubble, the result of my own conscious curation and not someone else's idea of what bubble I should be stuffed into.