AST gets the most love?

[Waemliht]

Playing well on a scholar in most content won't earn you many comms.
Using all your resources you can get through most things without ever using a gcd heal. The result is people end up getting low and staying that way until Regens or faerie heals get through. Anytime anyone looks at you you're probably casting briol. During mob pulls you're probably looking like you're going to run out of mana any minute spamming aoes. If they don't know what you're doing you're going to look like you're not taking your job as a healer seriously.

Idk about an ast but everyone else enjoys cards padding out their dps.

[Vyriah]

It's the cards.
When they get that balance they feel like they're the only warrior of light and that's why you get the comms.

[Risvertasashi]

The result is people end up getting low and staying that way until Regens or faerie heals get through.

From my own experiences, I feel like this is probably the most common reason. People like to be topped. Even if no one dies, letting people stay low doesn't seem to get comms as much as quickly getting them back to full or near enough. And... there was that 'study' someone did tracking a few hundred instances back at the start of HW that found similar. But, people here didn't like it because it wasn't a perfectly controlled experiment.

That said, the climate does shift a bit in a raid setting. I've heard people on pug voice comms comment things like "Both healers are 2k+? That's great." -- as long as no one's dying to lack of healing unavoidable damage, anyways.