My point is not that bows and crossbows aren't significantly different - they are, most particularly in terms of rate of fire - but rather that whatever their difference in military terms, I can't think of the difference as being relevant to a fantasy RPG adventurer. There are melee warriors, archery warriors, thieves, assassins, wizards, priests, and so forth, but the difference between a crossbow and a bow doesn't really make you a different character.
That said, if they've really decided to be somewhat realistic regarding crossbows' rate of fire, they would be largely useless for a dedicated archer in the game. One shot and then the enemy's gonna be one you, so they would primarily be (1) a decent first-shot attack for a melee warrior, and (2) something to hit flying dragons with. Thing is, for the melee warrior, a crossbow and bolts is a really significant amount of weight to devote when you know you;'re only gonna get that one shot it (it better be a good one) and given how many shots miss when using a bow, a radically lower rate of fire means a crossbow wouldn't be nearly as good for shooting at flying dragons as a bow.
The advantage you are not taking into account is the first shot quickshot.
This rate of fire argument does not apply if there is only 1 shot taken in an engagement, so it is fallacious to apply an avg. Rate of fire aregument to say- a snipe kill- or a quickshot followed by a charge- or a quick backwards feint and a loaded bolt shot.
This thing will have its uses.
I like crossbows.