Perhaps there is a class of people who pay for email apps. I'm not one of them. I don't see twitter as a platform, or at least don't use it as one. It is a communication medium which, for all my usage, could have no developer ecosystem.

Professionally I would love to have free access to the Firehose, that's some juicy data. But as a consumer Twitter 'apps' are no more worth my money than email apps.