sidegrade, inventory killing, no feeling of progression nightmare that needs 3rd party tools to play. yay!1) It looks ugly. Charactesr disappear every time they swap gear, I dont not want to blink in and out of reality the entire time I'm fighting. Not visually attractive.
2) Its overburdensome on inventory. We are getting a reduced amount of inventory spaces too, I can't have most of it taken up with gear. Sounds like a nightmare.
3) Its a balancing nightmare. As a dev, if you have gear swapping, how are you going to balance the content? Around a set of gear? Around Gear Swapping? Deciding a difficulty curve is pretty much a dice roll.
4) It alienates casual players, which eats away at a lot of profits. Once you have gear swapping, gear swapping becomes law. No gear swap no group. Oh you dont have 3 different sets as a tank? Too bad gtfo. Does the casual person have time to amass 3 sets of gear, all melded and ready to go? No. Do casuals mean more money? Yes. Therefore it is a bad idea to alienate casuals.
5) A game that is gear dependent is a bad game imo. If everything is dependent on gear (as in all problems are fixed with a gear swap), then it removes whatever challenge the game might have had if you could only use one set of gear. Unless they, of course, raise the difficulty curve...but in that case gear swapping woudl become a necessity, and casuals would be alienated. That is bad.
There are plenty of reasons for not employing gear swapping. It is a potential party nightmare..where everyone is required to have 6 sets of gear and multiple class/jobs maxed before they are even allowed to participate in group content. That kinda atmosphere is destructive to a game's health and longevity, turning away everyone but the hardcore few. The hardcore few cannot keep a game afloat, nor can they keep SE's investors happy.