I would love for them to revisit older classes; the worse thing you can do is leave them behind and outdated aesthetically. The fact they make it so rogue and ninja (within the same job/class advancement) has different animation is already going out of their way to design more for a class. Not that is a bad thing, but again we don't want them forgetting the classes/jobs that already exist because that can easily spiral out of control.

The way to word the question is "How do you make it look like each class has their own identity, just by looking at how they run?" I don't necessarily make them have drastically different running animation, but I really wouldn't mind having different ones for the classes that use two hands for a weapon (warriors, bards and dragoons) or having some difference between monk and paladin (and by extension...all the DoH/DoL classes)