tldr;

If you enjoy playing the game with healing only go ahead an do so. But be aware that at some point in the future you will start to dps or get bored because the tanks only need minor care if played well in dungeons or get frustrated in highend raids because healer dps saves a lot of wipes. If you dont care about those facts you will get along quite well but you will be flamed from time to time because most healers do help outside of their role.
The way the healer damage is constructed in FF14 (Large chunks are dealt by dots) it is definitly intended. If you want to dip in damage just try to swap to CS Dot one mob and switch out. That way you cant mess up the stancedance untill familiar. But don´t let People force you into damage if you feel you cant keep them up otherwise. Tell them they are too squishy or you would be willing to help if they start avoiding every third voidzone. Makes them think outside the MOARDPS-rooster. Even good healers cant dps if the group lacks skill.