I fail to see any problem with this whatsoever - after all, in the "bog standard" fantasy setting replete with requisite elves, dwarves, etc, the option to play as a human has almost always been fully intact. Then you have games like The Witcher, where you're not only human, you're always a specific male human whose name/face/voice/etc you cannot customize, and that game was brilliant.
Would it be cool to have an expanded arsenal of options? Well sure, but the story that Dragon Age 2 is telling differs from that of Origins, and the entire framing context really only works if Hawke is human, given the entire backstory and how it pertains to your family and their relationship with the city of Kirkwall. If you could choose to be a Dwarven or Elven version of Hawke they'd have to entirely rewrite massive sections of the game to make the lore "fit"; heck, at that point you'd basically have 3 or 4 different versions of the game based on race alone, even before you factor in player conduct.
So no, I don't think it's a problem that Hawke is always going to be a human, it fits the confines of the specific story they're setting out to tell, and it's not like there aren't elves and dwarves that you can be friends with and everything, you just aren't one yourself. There wasn't any significant gameplay mechanic behind that decision in the first game anyways, it was basically just a choice of which origin path you'd take and how other characters would react to your Warden, and other smaller things throughout (the stat differences between the three races were negligible). Otherwise, the rest of the game was basically the same no matter what race or class you played; the sequel isn't really much of a step back in that regard.
