That was only true in Gordias when DPS checks were insane and PLD was really underpowered.
Once PLD got buffed, they were doing comparable DPS as WAR/DRK and dps check weren't as tight.
PLD could have been viable at that time but their utility (and I include RoH, Delirium, Path debuffs) didn't fit well with the magic damage nature of fights. Hence, they were still left out.
I ain't saying that divine veil or the likes will make or break a fight but it still gives you more tools to recover or tackle a situation.
In V4S, the heal checks are really tight and divine veil, intervention and Passage of arms (and any other raid mitigation) do help significantly while we're undergeared.
