true enough, but a full maya scene importer would have a few problems. First of all, it would only work for Maya, glue works with any software. Second, things work a little differently in houdini, and it would be effectively impossible to exactly implement 100% of all functionality of the maya scene in houdini. cheats and hacks can get it most of the way there, but which cheats and which hacks gets very complex.
As far asa using glue to get rig information from a character setup, you could indeed do it with a lot of careful hscripting and naming conventions in Maya. It wouldn't be easy, though. and no moving the keyframes, true.
But who's going to start keyframing in maya and then finish keyframing in Houdini?