I'm going to counter argue with this:
Having 1 nuke and dot as opposed to several different abilities isn't a gameplay style or identity. WAR has its Fell Cleves on top of the 1-2-3 combo that all tanks share btw (not too different to all healers having a general nuke and dot). GNB who still has a 1-2-3 has cartridges (Gnashing Fang). DRK has knock off Fell Cleve and PLD has its own rotation. Once more for emphasis on top of the same 1-2-3 combo and ~5-7 mitigation options. If tanks can have that so can healers: a basic nuke and dot ON TOP OF something extra.
Your argument of keeping 1 healer without anything has 0 merit.
Edit: I'd also like to add, no one is going to truly care if a healer doesn't use their extra dps abilities outside of content that matters. Does it matter in MSQ dungeons? NO. Does it matter in EX and Savage? Yes. And in those instances, yes you should be doing your job to the best of your abilities. You signed up for that content. That is expected of you, period.
If anyone harasses someone in a duty finder MSQ/Normal Dungeon they can report it to the GMs and move on with their life. Is it the wrong way to do nothing but heal? Technically, yes. But you're still keeping everyone alive, it isn't a reportable offense. If the other party members want to kick you, that's their right to do so.