Re: Gearswapping. Most cases of gearswapping were no different from using any other stat-altering ability. Think of Warrior abilities like Berserk and Defender. Ultimately, they're no different from gear-swapping. It was just that everyone finally figured out that they could have these "abilities" all the time by switching their gear.
When these are done responsively in combat they reflect skill of the player-- e.g., switching into a water resist set right before being blasted by a water attack. When they're done as part of a regular rotation, they're just more steps to these optimal face-roll rotations that players frequently fall into, FFXI being no exception. They also made certain configurations possible... I enjoyed playing as SAM/rng for a long time only because I could swap into a ranged accuracy gear set.
So at times they were a great way to enhance the gameplay and embodied skillful play in the game. Other times they were just an annoying, funny-looking chore.
So what's the difference between the former and the latter, and how can we keep the one without the other? That's the question we should be asking. The answer that strikes me is to simply keep those mechanics while separating that particular functionality from the equipment. Basically, move those stat bonuses from the equipment grid to another grid, e.g., a crystal grid. Now in addition to trying to obtain equipment -which cannot be switched mid-combat- you're also seeking upgrades and sidegrades for your crystal grid, which you can switch out mid-combat to change your statistics in the middle of the battle in response to the situation.
That's one way to capitalize on what many players liked about gearswapping while dropping what many players hated about it. I suggested it in the first alpha (though I used materia at the time since materia didn't already exist); if anyone wants to try presenting it again feel free to C&P away.
It doesn't solve all the gameplay problems associated with gearswapping--for example, gearswapping for DD's was more often a set rotation that required little skill, because DD's largely do not interact with other party members (unless you count holding back to not draw hate). As a result, they have no opportunity for responsive play, little need for skill of any kind, and as a result are often happy just to have some more things to do, even if it's just activating a thoughtless ability like Berserk.