I'm with Nizzi here.
Although Dissipation could really use some adjustments to better fit into current time fight and toolkit designs, Dissipation isn't something that should just get nuked from our spellbooks.
I personally like the trade-off aspect and that you have to think about when to squeeze it in, whether you use it for healing with the additional AF or DPS. Although I dislike that we still have to spend a GCD on resumming our fairy after a death, Dissipation is useful for a quick AF snack during prog and especially after dying. It's also useful on p8s part 2 for replacing GCD heals with AF heals with much lower opportunity cost. We managed to trim every uptime GCD heal during part 2 right up to the later part of Dominion with this. It's also great for buffing downtime Spreadlos, I used to delay Dissipation on Carby to get a buffed Spreadlo off during jumps.

It's not a core part of the toolkit, no. On that I can agree.
But it does fit the trade-off/ opportunity cost design of SCH that makes you think more about when to use which skill, something I miss on the other healers. And despite having to pay opportunity cost, SCH is still one of the meta healers so it's not like it's the heavily punished niche healer that either doesn't heal enough or doesn't bring enough dps. It's in a great spot even with paying opportunity cost and having toolkit lockouts.