If it was there and the carseat fit my child best I wouldn't NOT buy the seat but I don't think I'd go out looking for a seat with that specific feature. I think I have too many kids to be able to forget them! :-P
i personaly dont think i would forget my child under normal circumstances but life is full of surprises and you never know its happened so many times with all kinds of people from all kinds of back grounds i think better to be safe than sorry