Balancing the game for <30 threat generation is a bad idea though. And even if you do lose aggro every now and then each dungeon, *most* people aren't going to get uppity about it. Those that do are either jerks that more threat generation wouldn't fix (because they'd be jerks about something else), or panicky newbies who think having a mob punch them in the face a few times while the tank gets aggro back = bad tanking (which sometimes it is, and sometimes it isn't - reality is, bad tanks just don't ever get aggro back, good tanks get on the mob ASAP or maybe let the aggro slip stay because it's on low HP and dies in 1 or 2 GCDs anyway). Both are things tanks just need to learn to deal with being the leader of the groups, if you never ate trash for other people's mistakes/not operating at 100% yourself then the role would be meaningless. That isn't to say that I take the insults as hits to my self-esteem and cry myself to sleep after every DF, it's just that to me, tanking is supposed to be for people who can take punishment and not let it get to them. In gear-terms and emotional terms. There's a reason most people just go DPS, and it has nothing to do with threat generation. Even with how easy tanking is in WoW, there's still a tank shortage. There will *always* be a tank shortage. The only thing developers can do is encourage the tanks that *do* play to queue up more often, which increased rewards will do. Most people aren't going to roll tank for added bonuses because if they could handle tanking they'd have done it in the first place, and the amount of people that'll make this change for the added incentive still won't make a dent in the numbers.
Yes you'll get attitude from Monks/Dragoons for repositioning while chasing mobs to get emnity back and things like that, but melee *always* complains about movement. If they didn't have to move, the game would get boring for them quickly as well since it would just be "stand still - do rotation", but there are absolutely melee that despise constant movement (and should've played ranged) and are *really* vocal about their discontent (due to boss mechanics or tank movement), you don't have to internalize their attitude or explain anything to them, just let them vent and keep going. Good players "get it", players that don't either haven't been playing long enough or never will "get it" because they have a bad attitude. Don't let it drag you down, don't internalize it, just keep the run going. Don't pick fights, don't give in to being baited into an argument, because both usually just *end* runs, and also keep in mind that sometimes the seemingly harsh criticism is coming from someone that is actually giving you good advice, but is emotional because you're the tank, if you make a mistake and they have to give you advice it's because your mistake just made the run harder for everyone. It's going to have some attitude behind it, even if they have good intentions.
If aggro didn't ping to players aside from the tank sometimes, tanking would be boring. Don't believe me, try WoW tanking in its current form. I absolutely do *not* want that with FFXIV.
What it sounds like people are saying is they don't like complaints, and if you don't want to hear complaints from other players you shouldn't play an MMO. Tanks screw positioning or lose aggro, Healers mismanage mana or accidentally go out-of-range and can't land a crucial heal, DPS misses rotation/CD management on DPS check fights or fails to blow an LB properly. Even if you do a flawless run, someone will find reason to complain. Making roles less fun will never change that, it'll just make playing amidst the complaints less rewarding.