So, I agree that there is a excessive amount of useless skills in in this game; however, I feel like the mechanics are perfectly fine. For instance, if your playing a gun slinger, you don't need to jump to different parts of the terrain to go into cover. Just press f where your standing and you'll pop a shield and it will be like you're behind terrain. Also, if you were playing a gunslinger correctly then cover would be your best friend; and master strike is almost just something to use to wear away the cooldowns on your other abilities that does decent damage, a filler if you will.
Secondly, I also agree that you should be able to use addons in this game; however, knowing how poorly this game's engine perfoms, I'm assuming it probably wouldn't be able to handle it lol.