I had two legendaries at the same time recently, one for my main stat, one pure crit I think. Can't complain here. It's all kinda irrelevant until we get to level 400 anyway (assuming we get a proper combat system one day), but at least legendaries last quite a few levels before being outclassed by epics.
It definitely matters - you will need weeks (if not months) of buying commons to get a single affection level.