Don't think its 60%. I've had whole games where it didn't break once. Its probably in the 12% region each minute, like I believe melee is without any WPF.
When I don't need to charge I can be shooting and reloading without impacting my overall affect on the round, while still having some semi random damage output. I've one shot plenty of guys with headshots, sometimes with body shots. Shot plenty of horses, got people dehorsed or just weakened them
At short ish range its quite effective on people who aren't expecting it. At medium range it's quite random, but if you aren't doing anything else a chance of a hit that does some damage is better than nothing. You need to use it while ranged are still exchanging shots and there isn't a melee yet, or otherwise keep it as a backup weapon. Fire into a crowd and chances are you will hit something. Eventhough reloading is pretty quick, you don't want to spend too long on reloading to the point were you aren't helping your team though, which can get to be a problem if you neglect your main role.
I don't really feel theres a good reason NOT to carry the xbow if you have 2 slots free, unless you spend all round using it and don't play to your main strengths. The only thing is upkeep really, and I don't really take much notice of it. Theres no restriction to my unloomed light crossbow either. The masterwork arbalasts I see lying around can be worth picking up for a quick shot too
The point of xbows is, that they are easy-to-use weapons. Every idiot can shoot with one, thats why you can use it without any wpf. If you have enough strength you can pick up any melee weapon and use it, just not very good.
And if you've ever played with 130+ wpf in xbow you know that with 1 wpf its not that good. Its a weapon for idiots, just like an ak47 is nowadays weapon for every dumbass.
Well you can say that about a lot of things in the game. Any idiot can pick up a throwing spear IRL. Anyone could jump on a horse if it was nearby and willing to take a rider. If you saw a bow on the ground and it wasn't a hard bow like Longbow then you could use it. Realism isn't a main focus on the game anyway, its all about the balance 90% of the time. I mean even crossbows aren't particularly realistic in the first place. You stand with a perfectly steady aim, no sight movement..reload while riding a horse etc