the UI and response time would need drastic improvements.

Also this just sounds annoying. now I have to make a macro to do my flying kick? Thanks for the offer, but I'll have to pass. Combos are already a bit hard to do because of latency issues. having to worry about jumping is just excessively complicated.

I think the keyboard method is fine. An option to filter jumping would be good, if it really becomes a problem when people are spamming jump.

Also: aside from fantasy/ridiculous settings you don't' generally jump during fights unless you are avoiding part of the environment around you. (someone throws a chair at you, etc.) Even then it's more of a lunge. I don't see a reason to include jumps in combat aside from Dragoon's signature jump ability.

now if you're jumping on/off a mount for/from mounted combat on the other hand...