Bill Gates made this mistake. Instead of cutting off the air supply of his competitors and landing his company in antitrust hell, he could have been a Force For Good by welcoming competition as a way to keep his company tough and on their toes and responsive to customers. It would have been good for business and made him a force for good.
Instead, he's giving money for education and health care, obvious good things, but places where his money is no better than anyone else's. Had he chosen to make less money 20 years ago the world would have been a better place today, not some day in the future.
For Twitter, doing good would mean decentralizing, not making every tweet flow through their servers. This makes the network weak, slow and fragile. To add bells and whistles to a flawed architecture is irresponsible and definintely not something a Force For Good would do.
People wonder if they'd still be a force if they decentralize. Of course they would. They'd be even bigger than before. On the web, people return to places that send them away. We could trust them because we'd have a choice. People don't trust entities that force themselves on you. Look at how hated Microsoft became and how Google is going the same way. Twitter's future is in their hands. They could either trust us to come back or force the issue. If they use force, eventually Twitter will break.
I use twitter.com when I could use any of dozens of clients. In the same way, in a decentralized loosely-coupled space, most people would use Twitter, as long as it remains reliable. And they would have an incentive to be the most reliable. Today we have no choice.
If they're worried about Google eating their lunch, or Microsoft, forget it. Look at the Buzz rollout for a clue. Google is too messed up by strategy taxes to be an effective competitor. Facebook might be a problem, but Twitter decentralizing would apply pressure for Facebook to decentralize. Look at all the upside there. Not just for Twitter shareholders, but for the web.
Finally a comment on the little popup cards. They break Twitter, as far as I'm concerned. Because of the 140-character limit, I have to be able to easily see the last few tweets for anyone I'm reading. And they need to read my tweet stream too. Try to get there (using Firefox/Mac at least). It requires a bunch of clicks to get the attention of the software. To replicate this paradigm on other sites makes me wonder if they're doing any real user testing at Twitter, Inc.