My greatest problem with twitter is that those whose who have something worth saying tend to talk an awful lot less than those with nothing to say.
I want twitter to be a feed of thoughts an opinions from people I respect, or important updates from companies I'm interested in.
I see a secondary value from twitter by people contributing to a conversation around an event, be that a sports game, a site outage, a traffic jam or an unfolding natural disaster.
Filtering out / systemically discouragingly a lot of the countless low-value/self promotional posts alongside a better hashtag (channel) view would be a great start.