I voted No.
The product, the G80, shouldn't have been delayed as nVidia was far overdue for a new architecture. However, I don't think that the options should have included only the Vista aspects of the G80. Doing so makes it seem like the OP is more concerned with another thread than other important aspects surrounding the launch.
I think it was a good time because:
A) nVidia (and us enthusiasts) needed something new.
B) It gives them a nice head-start cushion to work out the quirks, lower prices, and become more wide-spread than other DX10 cards arriving next year.
C) It let us finally stretch out the boundaries of certain DX9 games and play with high IQ and high frame-rates at the same time.
I do think that nVidia should have clarified their Vista support from the gates, but it's a little late for that.
But personally, I'm not in that much of a hurry to get a DX10 card or OS. I'll wait for the games to arrive and get patched (recently I've been getting games right when they hit the market and it has been more headaches than enjoyment), prices to fall and hardware to mature, and for Vista to get around SP1.