It's also common knowledge that arbitrarily changing a standard costs money. They have to educate hundreds of millions of users, re-jigger their databases and services, and forego a well known trademark feature of their product. Why bother? Everyone's memorized that it's 140 characters, and people have adapted pretty well to 140-character microblogging. Would 1,000 have been better? Possibly, possibly not. I think Twitter's fundamental problems run deeper than the SMS limitation; apart from some celebrity accounts with tens of millions of followers such as @RealDonaldTrump etc., they are starting to lose relevance compared to Facebook and other, more dynamic services.