do I hafta..

[Tsilyi]

DO YOU NEED TO DPS AS A HEALER : Absolutely not.

And her are a few more examples.

Do you need to use cool down as a tank? No.
Do you need to use heavy thrust as a dragoon? No.
Do you need to get greased lightning stacks as monk? Nope.
Do you need to use ninjutsu as a ninja? Not at all.
Do you need to use all the skills available to you on any class? Nope.

As much as I believe a comfortable healer can and probably should dps (and I would), these are about the most asinine arguments I could possibly imagine to justify it. For a dps to not do what you are suggesting would require them to actively avoid doing so. That kind of example is not an effective argument...