I don't know who over-sold you on PLDs being stun-bots, but you really have to do it for 2 fights only, and that's only if you happen to be stun-bot and not MT.

As stated before, people use PLDs because they have stun on GCD, so its the most reliable, and if you over-stun (3 or more in 30s) they will get resisted. Therefore, you set ONE person to do stuns, so you know no one else will screw the pooch or over-stun, ban everyone else from stunning, and use the most reliably available stun, thus PLD.

But really, its not that bad - you'll do it a few times then not have to worry about it so much any more : D