You asked...
Why do we need MX for ShootMania? Well, because it's part of ManiaPlanet.
MX will probably support any ManiaPlanet titles in the future, even QuestMania. It may be a different genre, but ShootMania is still very closely related to TrackMania.... how you build maps, share them, etc.
We supported all the TrackMania titles in the past, even ones that some players didn't care about. Some users didn't care about TMNF, but we supported it, even giving it its own sub-site. And they just hit a third of a million tracks. Surely a lot of users are thankful for having that site.
And just because your circle of friends aren't going to play ShootMania, it doesn't mean that no one here will. There's plenty of interest in it both in the ShootMania topic in the General forum here and from a lot of TM players talking about it in the ShootMania subforum on ManiaPlanet forums.
I personally don't plan to play it as much as TM. I'm still mostly a racing fan, always will be. But it will be a nice side thing to play and will even be fun to make some maps in it, once I figure out exactly what kind of maps I want to build.
Much of the code base for MX for ShootMania is already taken from this site, so it's not a huge thing to make I guess. It will just require a bit of reworking for some of the details I guess.
But looking at it from the other direction... ShootMania could bring a whole lot of new people to TM2. If they like the editor and are curious about building some race maps, they might pick up Canyon. And if they're already familiar with MX for ShootMania, they may find it easy to jump over here to MX for TM2.
Now, I'm gonna go back to adding authors to my favorites....