The reason that there aren't any good audio games hasn't got anything to do with the language used. It has everything to do with the fact that there just aren't that many experienced developers working on them. There's a lot of people with pie in the sky ideas but not that many who have the luxury to devote there time to really making one. After all, no one will make a living on making audio games. There just aren't enough blind people who will pay for them.
Also there seem to be a lot of lone wolves out there (me included) who try to do stuff on their own because they don't know how to network, aren't use to it, or whatever. Big games take teams. Of course there are always going to be exceptions like BK3 and a handful of others that could be considered "big projects," but that's the exception, not the rule.
As for learning programming, no matter what code base you are using there are concepts that are universal: loops, objects, conditionals, level design, etc. It doesn't matter where you learn those concepts. The syntax changes, but not the ideas.
I'd rather someone spend time learning those core concepts than wasting their time trying to just get a language running. I don't use BGT. I used C++ for a long time and now I'm switching to Python for my own reasons. But I don't care what recipe or oven someone uses. I only care if they can bake the cake.
You can follow me on twitter @s_luttrell and an almost never used Facebook account at skluttrell.