Its not that hard really, especially when you consider we have the bullet object, in fact I would wager that you can do more from eventing than you could using xml.
Besides, the drawbacks are pretty big:
A: A ton of objects in javascript is a bad idea to begin with.
B: Xml would require additional libraries, Ios, Ie, etc. don't support it.
C: You are limited to what commands are available to Bml, whereas in C2 you can do what ever you like, hence my question of what can it do that C2 can't.
Try it on your own, you might like it. If you need suggestions... ask away.
Complaining that nobody wants to make you something, bad idea.