The lower-level Inflict spells only seem super useful for healing undead and as an improvised weapon for necromancers who have GSF.
To the point I can only recall one PC who bothered to prepare Inflict Light or Moderate and use it on the regular as a weapon.
I really want to use Inflicts for Holy Smiting, but it's just better to prep Cures as those Always Work and require no investment. Anything I really want to Inflict probably has good AC or good Will, but I can buff my touch attack AB way easier than my Save DC.
(edited thanks to a discussion on player-advice)
Specifically I'm comparing it to cantrips, which are only doing 1d4+1 (except Starblight) but doing it six times as often as Inflict. Without taking up a real spellslot, without the chance to lose them if you get hit while casting, and often having a chance to do a rider effect with GSF. They are a better 'do a small thing to participate' tool. to the point I will generally see Priests walk over to club some half-dead flanker to death with their relic before I see them pop an Inflict on it.
You need some Dex, GSF Necro and probably Blind Fight to be able to land Inflicts, especially if you plan to use them in PvP. Inflict Minor, Light and Moderate are particular miserable with their lower DCs, but those are the slots you can spare for a bit of plinking.
I'm not really considering 'slamming something with an Inflict Crit as one of those every 30s is serious damage'.
I am saying 'Hey, wouldn't it be cool if 1-2 Inflict Light or Moderates were a better backup melee plan for a Priest than Big Club? That feels more thematic.
If there's a worry about balance (Inf Crit is big, I get it) you could just remove it off Inflict Minor and Light and see how it goes. As the damage on those compares badly to "I could just flail with this Club with MW, when I'm not healing". Sure I hit less, but it's not too hard to get a 2-10 Club or something, and I'm swinging that twice a round.
Priest Cure Spells Vs undead are pretty good because they don't actually get a Will save, you just need to land the touch attack. And if there's no undead around you can still heal. And yet nobody is complaining that Priest heal spam trivialises undead quests! The difference between 'trying to use Inflicts on living NPCs' and 'trying to use Cure on undead ones' has been like night and day.
But having to beat Touch AC, Will and potentially Concealment is rough. Ghoul Touch and Healing Sting lost the touch attack because DMs recognised that a spell that has to beat two defences is super weak. Could we lose the Will save on Inflict? It's nice to have somthing that can reasonably threaten bosses and PCs that have Big Will (everything wants Big Will).
Alternatively, take the Touch Attack off. Then GSF Necro gives you bigger damage but you don't have 2 ways to miss.
Thinking about it, the other way these would be more useable for non-specialists would be if Cure spells regenerated even if spontaneously used to cast Inflicts. They'd still be Not Great on the lower levels, but they'd let you burn through a heal surplus when you had it, rather than have it sit waiting.
As it is, an Inflict is a slot you don't have a Heal in, and a small Heal is just generally better as it always skews the combat balance in favour of your side.