The problem is, none of the engines so far even come close to the quality of decent game engines on other platforms. They've all got seriously rough edges, bugs, missing features, etc., to a point where there's not even a clear winner yet where further community development efforts get funneled.

Until there's a clear "winner" in the space, I'm happy to see more engines come out, maybe one of them will finally get close enough to a general purpose game engine that it will see some community involvement.