This was touched upon in several other threads, but I felt its own thread would do it some good...
The thought that started it was this:
Remember those games in which you couldn't jump? So, you came to terms with that, but then you got to some place where it became excrutiatingly frustrating that you couldn't jump, because another part of the level was 2 feet away.
Well, isometric cRPGs tend to follow this "no active jumping" trend, and sometimes the level design has something you COULD easily jump (hell, probably even step) across to, but you can't. And yeah, the terrain and areas should probably just be designed differently IF you can't jump.
BUT, what if you could? A realistic kind of jump. You know, a distance jump, not so much a 10-foot vertical leap or anything. But, what if you could have an agile, acrobatic character who was better at jumping, and that allowed you to get to certain plateaus (jump across small cliff gaps or raging rapids, etc.)?
The Jump ability, for example, could be ground-targeted, and the higher the skill (and/or stat), the longer the range (just like targeting an AoE spell/ability). You could even jump across gaps, carrying one end of some rope, and tie it off on the other end to construct a makeshift "bridge" for the not-so-jumptastic members of your party to get across. That's just one potential use for it.
You could also have some quest with the goal of figuring out what so-and-so is up to, in the upper portion of some building, and jumping could provide one of your characters access to the rooftop of that building (from an adjacent rooftop of an accessible building), so you wouldn't have to talk your way in or get to it by other means. *shrug*. Again, just an example option.
The same could go for Climbing, really. Climbing certain walls and such.
*shrug*. 'Twas just a kind of mental image I had, that lead to some thoughts, that led to a thread.