Tera has 3 game modes that have equalized gear (Gridrion, Corsairs Stronghold, and then the Kumas you mentioned) and only one two that are non-equalized outside of the weekly server wide pvp event.
As for being complicated, yes there is a lot more going on and it takes a little bit of time investment to figure everything out, but most everything is easy to find. All of the min/maxing of stats that you need, which is slightly more in depth than "just get as much of everything as you can," skill rotation/priority orders, and all sorts of other guides are readily available to players, either through the player made essentialmana website or the class discords; which are similar to the BNS Academy Discord.
The game is honestly more grind to win than pay to win. There are a few boxes that hit the store occasionally with mats in them...but even the pvp is just grind till you get enough mats and pray RNG is on your side upgrading. (The low RNG factor in BNS gearing is the main reason I play the game...)
Also...only tanks are lacking in Tera and if anything, there are too may healers xD
For a time, everyone and their dog had a healer alt because the gear req. to farm was so much lower.