A lot of Japanese people use Twitter quite effectively as a micro-blog. This is harder in English because of the character counts. So it could be that "Japanese-style twitter" is the true product vision, and it's not working in English The original 140-character constraint was an external restriction from formatting, it could be that 280-characters is, in fact, the "right" number of characters for the service they want.

So many people complain about the overly-terse nature of tweets. This can help tackle this and get to a better product.