Why are Paladins usually on stun duty? I'm confused.

[Saccharin]

I levelled a paladin to 50 during open beta and into launch and one thing that's always annoyed me - the stun in on the global cooldown. It's always been an annoyance and something I just reluctantly accepted. I did the HM primals as the paladin stun tank and I had no issue with it since I hadn't done them before so a stun tank was a nice first try to see the encounter with out wiping the group.

So I got my relic zenith and basically abandoned my paladin job because it was really boring and other issues that I wont go into. Recently in the last few weeks I decided to level a marauder since I have Monk, Bard and also WHM to 50. The first thing I noticed is that marauders have a stun and it's even better it's off the global cooldown. Now on my paladin if I want to stun any ability just to stop the adds/trash I have to wait until the global is done and with tight casts I miss it. On my marauder it matters not one bit since it's off the cooldown and I use it often, even for extra damage to save TP.

I don't understand why paladins are asked to stun considering warriors have a far more useful stun that's off the global cooldown. No need to wait for the spell to cast just smash things and then stun when it's time. This is one of the best thing I like about warriors but at heart I'm a shield kind of guy.

I did a quick search and it's been unsurprisingly been brought up before that the paladin stun should be off the global cooldown, why not. I'm never for homogenisation of classes but it's such a large quality of life improvement and an off GCD.

So all that and I ask why a paladin, with an inferior stun, is usually on stun duty. I'm confused and seek your wisdom oh wise forum posters.