I see you have an older version of the PHB which gave access to Divination to more than was supposed to be available.
Although, I don’t think I’ve ever seen “any” in the race column before. It usually has Humans & Gnomes.
This was corrected later, but honestly, Gnomish diviners didn’t seem that odd thematically either. Gnomes did get access to Artificers school in PO:S&M.
Wu Jen were a kit in the wizards handbook and never really a unique class in 2E. Wild magic and elemental magic were in the ToM as distinct specialist classes.
PO:S&M expanded this to create different types of spell identification, Schools of Philosophy—same as the PHB; Schools of Effect—elementalist from ToM, with dimensionalist, force mage, mentalist, and shadow mage; and Schools of Thaumaturgy—wild mage from ToM, alchemist, artificer, geometer, and song mage.
The other biggest addition to the wizard group was from Al Qadim and Dark Sun, the former of which added the sorcerer (basically a modification of the elemental wizard who has access to two elements but without the benefit of specialization), elementalist (basically straight from the ToM), and the sha’ir who accessed magic via genies. Dark Sun had the preservers and defilers which really felt like it was something that came from the zeitgeist of the late 80s/early 90s ecological pop science, which unlike today was much more focused on pollution and resource conservation rather than greenhouse gases & climate change. Oddly, even though that wasn’t a huge part of the discussion at the time, we see magic-caused desertification showing up in a few different places, Dark Sun being the most prominent, but also in Forgotten Realms in both Anauroch and Raurin deserts.
All in all, the 2E approach to magic was extremely extensible without having to really add any extra complexity.