Not being able to click on targets that are OOR is irritating as hell, I totally agree.
Dimming them like in WoW would be a start, so I can triage right away w/o trying to target the poor sucker 3x before realizing that he is too far away again.
I've got a PC with 8GB RAM, there is no reason at all that the limitations of some shitty ancient console-toaster should apply to my game... esp not in PvE scenarios...