I've been thinking about how melee almost always have a harder time getting their combos off when compared to ranged classes. It makes melee less likely to be selected for a pick-up group because of how much more knowledge and a little bit of luck is required to compete with how easily BLM can do their max dps. So my idea is:

Make combos guaranteed to activate their next chain but have some extra benefit to doing it in the correct locations.

Now I haven't looked at all the combo bonuses but I'm sure there are ways to make a properly chained combo be noticeably more beneficial than a combo that is executed without moving. It would at the very least allow for some user error and not end a combo because you were a couple feet in the wrong position and the server considered it an attack from behind instead of the left/right.

DISCLAIMER I am not saying make full strength combos executable from any location. Simply make a combo weaker when executed from the wrong location but keep the combo chain alive.