Why Don't Developers Harness .Mac?

I love my .Mac account. Aside from the typical shortcomings some users complain about – zillions of GB of space, iDisk speed boosts, etc. – I truly feel it's an amazing concept with a ton of potential that's been implimented really well so far. But with all this power just lying around, why aren't more software developers leveraging the power of .Mac?

Transmit, my favorite FTP app, uses Tiger-specific .Mac capabilities to sync favorite sites. I just downloaded Smultron – an open source text editor that syncs preferences via .Mac – on Jay's recommendation. This kind of stuff is incredibly handy, and if you think about it: if more apps did stuff like this it would propel .Mac's usefulness to new heights. So what's the problem? Are .Mac subscription numbers growing slower than I thought? Are developers having trouble finding the SDK? There's so much potential for .Mac that my iMac and PowerBook are almost dripping with it. So I ask you, TUAW readers: why haven't more developers hopped on the .Mac bandwagon?