Have you considered the possibility that people play healers because they enjoy healing? And that maybe the answer to healer population is to make healers A: Feel necessary, B: Satisfying and C: Fun? A decent part of the healer problem is that other roles are getting an increasing amount of our job making healers feel unnecessary, damage being large scripted and spikey further degrades the necessity of healers and serves only to make healing unsatisfying; especially as healer optimisation is ironically to remove the healer. All of which results in healing not being fun. So you have healers that are A: Unnecessary, B: Not satisfying and C: Not fun and then people wonder why people don't play them.

Then you come along and tell us that the solution is to degrade these things even further...