First off, Twitter is social media, yes. However, it is a nice place to meet other people and learn about other cultures.
Secondly, Twitter is a good place to chat with people from other nations and cultures.
140 characters is not enough space to have a nice conversation with someone from another nation, or an old friend.
I think Twitter is made to be to limited. It is just meant to be like that. There's always inbox in Twitter if you're afraid you can't talk to somebody new. And anyway, there is so many other social media if you want to be able to write up long posts like fb, tumblr etc.
Eh...Maybe people will learn to be concise on Twitter. Short but expressive and to the point. And you could always post some more tweets as continuous to the previous. And there's also the question of extending the word limit to how many exactly.