Honestly for low-damage healers they're mostly going to get the side-eye because they're almost always low-CPM healers, too. Like, you pull up somebody who talks about needing to always be prepared for PUGs running in to danger, and there's a good chance they're hovering below 20 CPM. Which means they really are doing nothing most of the time--and them actually realizing how much time they spend not doing anything will be a huge part of them realizing there are DPS windows.
20 is a really, really low bar to cross. If you'r reliably under that, you're probably spending a lot more time doing nothing than you think. And at that point it's just a learning thing. Your damage output doesn't need to be amazing, but you also shouldn't be telling yourself you're doing the best you can be expected to do in content when you're spending half your time not doing anything.
I wouldn't agree that the main reason WHM is top healer has to do with dps. They got great actual healing abilities whereas AST fell off a fucking cliff because the new card system doesn't feel nearly as good as the old system and your healing ability is significantly worse off. Scholar is just fine though using your pet isn't a great as it used to be because of the overall pet changes.
But the damage component is why WHM is widely regarded to
feel the best; the job has a loop that directly rewards GCD healing with free damage. Healing on WHM doesn't feel particularly like anything, because everything is OP and there's not a lot of strategy to getting people healed up. AST has the more involved healing system right now, but stacked up next to SCH and WHM it feels like ineffectual busy work there's no real reason to put up with. But where WHM excels is by having the Blood Lily as a sort of reward for healing. AST gets nada, and it sucks, but slapping a damage reward onto the busywork would go a long way towards making it feel worth. Buffing AST healing potency will make it more likely to be taken for prog, but is unlikely to make the job really feel better to play, because it's still a bunch of fiddly BS with minimal payoff.