Well, first off, a lot of people don't want new skills because there is already enough skill bloat.

The other thing -- PLD already has everything. They've always been the most complete tank. The problem isn't that they don't have something, it's that what they have doesn't do enough for various reasons.

PLDs have AoE. It's just that Circle of Scorn has a long CD and doesn't do enough damage. Flash generates AoE enmity but doesn't deal any damage.

The biggest thing they have to look at with PLD is internal synergy and how it can be used to make their overall skill-set less situational and more fluid. For example, in magic damage heavy fights, they need to figure out a way to keep Bulwark and Sheltron relevant. In fights where there is no knock-back mechanic, they need to keep Tempered Will relevant. When PLDs don't need enmity, Rage of Halone still needs to be relevant. When PLDs aren't taking damage, Rampart, Sentinel, and all their other dCDs still need to have some use.