That's exactly what I was thinking was the reason for doing it (although I didn't consider the possbility of V being her father, or pick up the "Evey-man" thing, which seems obvious now. Duh.) Emotionally, it made perfect sense and had to happen - I just wish they could have made it logically inevitable as well. But that wasn't enough to really spoil anything for me.
Apparently Alan Moore is a bit of an odd duck - I guess he had a huge falling out with Vertigo comics (I don't know over what) and has decided to stop writing for comics altogether and just write wild, angry Letters to the Editor with his unconventional opinions. Too bad - talented guy, obviously.