Hmm, never tried it, but makes sense. An added benefit also is that when you grill things, you end up burning little bits of the meat, which is not great for your health. This method seems to cook similar to boiling.
My only doubt is about heating food while it's in contact with plastic (bags) or vice versa. I understand there is bleed from plastic onto food, this is why it's not recommended to heat things for too long in plastic inside a microwave or let you plastic water bottle in a locked car under the sun.
Aside from this, sounds like I would try it.