I feel like _A_ healer working this way (SGE should have, honestly) would make sense. Not all of them, but one working like this could be interesting. That way people know what they're getting into when they pick that one.

The problem of gating heals behind damage is that it makes it difficult for new healers or certain situations. For example, on SGE, when you ARE having to GCD heal a lot, you aren't getting Kardia procs. Now take that and extend it to having abilities that are locked until you do damage and...yeah, it doesn't always work.

Again, one healer Job working this way is probably fine and their kit would be designed around manipulating this in various ways. But all the healers being forced to this would probably not be so great. Even if it was something subtle that didn't affect healing at all - e.g. suppose SCH had Energy Drain on a 20 sec CD instead of costing AF, and casting Broil cut the CD by 5 sec each cast - you'd still have problems of people chading their co-healer to get better parses. But at least that wouldn't (generally) be wiping the party where lacking an essential heal at a critical time could do so more consistently.