MrPopo wrote: and Microsoft made a point of courting the shmups devs
This is the core of it.
I said the same thing in the shmups.com thread: I'm a Linux systems admin and infrastructure architect. My job is designing and rolling out large Linux systems. I've seen first hand the lengths Microsoft will go to in order to try and tempt you away from your current platform of choice. Everything from cheap (and sometimes free) first round licenses, development kits, development subscriptions, etc through to just good old fashioned schmoozing (golf days, free beers and titty bars).
Note that I'll say straight up this isn't limited to Microsoft in any way shape or form. It's corporate 101. But that's exactly what's going on over in shmup land at the moment. For small studios, dev kits and fees are big bikkies, so when Microsoft knocks on your door with olive branch extended, you take it.
There's a lot of people who want Cave (and others) to embrace Steam as their distribution system. IMHO that won't happen until Steam do a better job of localisation in Japan (which means more than just putting Japanese text on their website, but offering sales in Japanese yet at a fixed price, and maybe even Japanese phone support). The Japanese are a fiercely loyal nation, and the only way to court them is a strong local presence (and often face to face). And it should be noted that Microsoft is doing a very good job of that, after the failure of the original XBox in Japan.