Healers that don't want to DPS are like DPSes who refuse to move out of AoEs.

[Faliandra]

...some of the dps abilites you won't be using in practice, like fluid aura ...

Ehhh...why not? I use it ALL. THE. TIME.

Even in casual roulette content, there are plenty of mobs at later levels, that DO NOT get a knockback, so its a great filler skill to use.
If im not sure if it causes a knock back or not, I'll just use it when the mob's hp is low enough to get killed off by it, so whether it gets knocked back or not doesnt really matter.
If it still survives, well, then I'll take care of it if you just let me finish another 2 second cast that it will take to kill it . Dont run after it and complain i knocked it back. Especially not when theres another mob next to you you could be hitting instead.

In any trials or raids,it will never cause a knock back, so not using it is a big potential dps waste.

Also, in some cases it can even be used as a way to interrupt a mob's cast that you dont want to go off (although i dont really use it that way...or, very rarely at least)