Earlier quoted context omitted.
There's an interesting startup that I think does that. It's called Facebook.
Then why are people using Twitter then ? You cant say Facebook is like Twitter with more characters in the messages,it simply doesnt work.
Because Twitter has a lower barrier to entry. Yes the 140 character limit sucks. But because of the character limit, people are more inclined to open Twitter in the first place. The psychological advantage of that outweights the disadvantage of hitting the 140 character limit later, at least for users.