The question is if you are ok with being just adequate. If so, then you can continue being just that. Just as there are Tanks that will never use CDs, DPS that don't use any of their cooldowns, there are healers that will never DPS.

And that's fine for most of the content in this game. When I heal there are situations where if I don't throw down some DPS I could potentially fall asleep. Healing is definitely the easiest job in 4-man content, no questions asked. However, there are situations outside of 4-man content where it's not so easy to do the switch between healing and DPS.