so that you can steam chat or download a game or something?
what's the point of not running steam with minecraft if you don't have an ass pc.
unless you're running minecraft in fullscreen mode, there really is no point since you can still chat while playing, just pause and click outside the window. downloading a game would be even less of a problem. it's like running chrome with steam. the ingame interface is known to forget stuff up on non-steam games.
"because i can" is a rather invalid answer.