Healer role needs more love in general~
We need the possibility of a healer build using Stamina so that more healers exist. If you play a Stamina character you only have the option of making that character a tank as well and some would prefer healer instead. Many will still pick neither though because the majority of MMO populations in any game will always play DPS but you need to do everything you can to make those roles more desirable and easier to access so that queues don't take 11 years.
The "Holy Trinity" has always been a flawed system and you're going to need to allow people to fill multiple roles without having to sink gold and time to swapping everything back and forth. You also don't really have the time to swap between roles quickly when queue actually pops and tells you what you're going to be. So for example you can make some Stamina cost heals/buffs, allow saving builds you can swap between, don't be too picky about inventory limits with crafting bag and 0 storage systems from housing so people can actually have two sets of gear.