I want to start out by saying that I am not the most experience white mage player ever, I am also in no way claiming that white mage isn't viable or that it cannot clear all the content in the game in its current state I am only saying that there have been several changes or lack there of to whm that, in my mind, make the job worse to play for no reason.
My goal with this post it to put everything that I think needs to be improved about whm in one place. I have seen some good discussion here and there in other posts but no posts that attempt to concisely summary where white mage need improvements and propose possible fixes. Maybe if we are lucky the devs will see this post and others like it and get some inspiration for where to take white mage since they don't really seem to have a solid direction for it right now.
Firstly, white mage's mp economy and recovery potential. Frankly whm has awful mp economy and post death recover at the moment. As far as I can tell it is currently the weakest of all the healers in these categories and especially when compared next to its pure healer counterpart astrologian who, when played well has functionally infinite mp. The combination of the nerf to thin air, loosing lilies on death and high mana costs really hamper whm's ability to function well in any situation where high pressure is put on their mp supply. I think the solution to this is very simple, lower the white mage's mana costs to be in line with astro, buff its base mp regen and maybe make thin air apply to the next two spells instead of one or something similar. I think this would go a long way to easing whm's mp problem.
Secondly, the lilies. This is probably the strangest issue that white mage faces at the moment and kind of shows how little care was put into their endwalker changes. While lilies were always "a dps loss" because misery didn't have the potency of four glares and instead was kind of like casting three glares and one healing gcd it isn't even that anymore. Now that glare has a potency of 310 while misery is still 900, lilies are no longer even equal to "3 glares and a healing gcd." On top of this, solace and rapture are no longer required for weaving windows because of glare's reduced cast time. All together the way everything shakes out, whm is discouraged from using its lilies at all, as now you would just rather use 3 actual glares and medica II. This might not be that big of a deal outside of optimizing play but its an issue that doesn't need to exist and frankly shouldn't. Fixing this is as simple as raising misery's potency to 930, though in a perfect world I actually think misery's potency should be around 1300 which I'll discuses further down.