The 30% cut Steam takes is quite a bit. Considering the near-monopoly it has on game distribution, that could easily mean the difference between turning a profit and not for an indie developer.
Personally their efforts towards things I support (PC handhelds, Linux gaming) and the convenience of the platform outweigh the things I dislike, but being frustrated by its problems is understandable when people don't really have another choice.
Error 404: Costume Not Found is a classic.