The only time I find it really problematic is in large scale PvP or 24 mans when I'm trying to target someone outside my party to heal. It's really difficult to click target characters that are moving for some reason. The other way to target them requires a click on the alliance UI but that's even worse because you have to scan the entire thing to figure out where that one person in that mess is if there are multiple of the same job in the same party. Usually they're dead by that time in PvP. For mobs I can just use the enemy list or camera manipulation.