Well it's more just most people want to see each job look stronger, to feel like they've "leveled up" since you are quite literally leveling up another 10 levels with each expansion, and to also add something new to each job's gameplay. That's one of the dilemmas of a live service game--each major update kind of asks you to reinvent the wheel because if you don't, you'll run the risk of people losing interest over time. And to be fair, they have been doing that with healing and support actions, but there's a problem with that because they have never scaled up the content to match these new healing and support tools. Our healing libraries largely feel bloated and excessive because there's rarely a reason to use half the stuff we have these days. Extreme and Savage might push us to using more or all of those cooldowns, but many of those could just be supplemented with GCD healing if we didn't have those extra cooldowns.

And it's not that there needs to be another layer of complexity added every expansion, but things that can seek to smoothen out different aspects. For example, maybe you change Afflatus Misery from 1 button that's 1240 buttons to, with regards to Glare III being 310 Potency, 2 spells that are 775 potency each, or even 3 spells at 620 potency each, with each spell being on the same button similar to RDM's Verflare/Verholy, Scortch, and Resolution. Something like that would make your blood lilies feel more exciting for some, but functionally could make crit variance less polarizing.