They're doing it now because, when the weather gets bad and everyone wants to come back in on their bikes, they'll be over the sticker shock and will just pay up. Short term pain of extra people dropping now to be followed by long term gain of added revenue (and almost everyone coming back) when the winter comes from Z's point of view.

Had one of the competitors (especially one of the free ones) had a killer competition ready to go (ZRL clone, maybe), it might be a different story, but they weren't ready for it.