It's not in a bad position where it is now. I mean you can't change jobs when Enmity is generated and you can't change gear in active mode and that nips most of the problems in the bud. I suppose they could make it where you can't change jobs/gear in instances or dungeons too, but that might open up another can of worms.

For example, your tanks been away from town all day, your in Cutters Cry and his armor breaks. He can't swap to another piece of armor and his pal who has 50 Armorer can't switch over to fix his stuff, so now the groups stuck with a tank wearing broken gear.

It might be a more extreme example, but truth is your not going create any kind of system that does not have it's own kinds of problems, nor a system that everyone is going to be pleased with. As it stands I think it's a good balance, and as slow as the UI is in this game I would think Active Gear Swapping would only compound the problem.