Agreed. I have no way of being certain, but I have to believe the use of Vala for projects like this (and Shotwell, etc) have a negative affect on community contribution. Not saying that's a reason to use another language, but I'd bet the choice of python, C/C++, or something else would deepen the pool of potential contributors. I for one would rather not learn yet another language simply to contribute to Gnome projects, much in the same way I've never been a big fan of having to learn Obj-C for Apple-based projects; I simply don't think I'd use Vala or Obj-C outside of those contexts.
That said, there may be very valid reasons which are performance or convenience-related for choosing Vala. Would be interested in a discussion of those if so.
For reference, Vala looks like a bastardised C# which compiles down to C which then compiles to native. The whole thing is built on top of Glib and GObject, the latter being akin to gouging your eyes out with a fork.
