Weclock: Actually, they are (valve). It's the same updates that PC users got for free.
But I seriously don't think that the DLC should be free for Fallout 3, they had expansion discs for Oblivion, and for morrowind, that you had to pay for, and they should continue that trend.
Yeah Valve wanted Microsoft to offer them for free, but of course not.
It would be a good idea to eventually offer the DLC on a disk ala Knights of the Nine. They shouldn't wait though and put it all on a disc, though.
The main appeal of DLC is that it's cheap and for 5-10 bux it's a "What the hell?" buy. This is how GOG operates. The games are only 5 -10 bux and noone minds tossing such a small amount of money for quick delivery and fun.
But seriously once the G.E.C.K. is out, who cares about paying for content? There will be so much user generated stuff that you could easily forget about the official DLCs.