Concepts from other MMOs that would be utterly anathema to FFXIV

[Shurrikhan]

I honestly Wish ffxiv would use a spec system honestly...

I might even be fine with just having some slightly less clear-cut shared-CD actions and more significant stat effects that are more conveniently set (e.g. being able to choose between two secondary stat choices per gear piece, and choosing breakpoints to keep to between them).

Some jobs have good deal of difference in playflow available to them just by switching between GCD speeds.

In general I'm wary of choices for the sake of choices, but having several playflow variants or a few other significant changes per job can be worth their development costs insofar as they increase the breadth of attraction of jobs that might otherwise be overlooked.

Anything that increases the product of breadth and depth of attraction to players more than it increases the development costs necessary, without decreasing overall cohesion, will likely be good design.