What do you want for free? Do users have to pay up to complain?
Matt Asay excorates the whining masses that are taking Twitter to task for its ill-considered removal of the @replies feature. Asay says "pay money so that you actually have the right to voice your displeasure as a customer rather than as a user." However, Asay misses a glaringly obvious point here -- Twitter hasn't given anybody the ability to pay up.
In general, I do agree with Asay that being a user isn't enough to give someone the right to complain -- or, at least, the right to be taken seriously. For open source projects, there needs to be some kind of consideration before taking a seat at the table -- either as a contributor or customer. If you're putting in sweat equity to a project, rather than cold hard cash, you should be taken seriously.
And, of course, money talks: Customers should expect their complaints to be heard, and acted on when possible and practical.
But the folks at Twitter are still finding their way, and the only option users have is to be loud in the hopes of being heard -- or using alternate services like identi.ca which puts the power in the hands of its community directly. While Twitter is still trying to figure out what it wants to be when it grows up, its community doesn't have the opportunity to "pay up" -- either in contributions or money.
Right now, the only business that Twitter seems to be in is building out its user base: Which makes the complaints of its community quite valid indeed, whether or not they've sent a check. Depending on what business model Twitter ultimately chooses, just being an active user may be a valuable contribution in and of itself. (Assuming Twitter goes with some kind of advertising model.)
Asay's suggestion that a predictable service is a premium business model leaves me a bit cold. Enterprise Linux distros have very little in common with Twitter, and the expectations for enterprise OSes are rather different than those for a microblogging service.
Right now, Twitter has something which Identi.ca doesn't yet have: Momentum. But if the service continues to futz with the service and treating users like an afterthought, that may change.