The author describes reasons why the 140 character limit is a problem (e.g. you can't have long conversations), in which they absolutely miss the point. Twitter is not meant to solve all of your communication needs. The 140 character limit allows Twitter to be a reliable source of quick bits of information - you can dive deeper if you want, but it's a great cursory overview.
Tools don't have to solve every problem. They can (and probably should) solve one specific problem really well. Twitter does that.