Back on the original topic for a moment.
One advantage of 2nd ed was the more clarified division of "groups" and "classes" instead of "classes" and "sub-classes." In 1st ed, if a rule referred to "fighters" you couldn't really be sure if it also applied to paladins and rangers, because those were sub-classes of the fighter class. In 2e, all three are classes in the Warrior group, so it's clear that "fighter" does not include "paladin."
However, one side effect of this was the merging of spell lists - the cleric and the druid lists were merged into a general priest list, and each class got access to a subset as defined by the spheres (and similarly for the magic-user and illusionist lists being merged into the wizard list). On one hand, this made it easier to add classes - it's a lot easier to say "A Wonderbringer of Gond has major access to All, Astral, Combat, Divination, Elemental, Protection, and Sun; and minor access to Charm, Guardian, and Healing" than it is to provide a spell list taking up maybe 15 pages or more. On the other, it lead to some weird stuff, like moonbeam being a 5th level priest spell that gave weak illumination to a small area for a short time, and continual light being a 3rd level priest spell that provides very strong illumination in a huge area permanently. The reason is, of course, that moonbeam used to be a druid spell and continual light a cleric spell, but as someone who started with 2e it made no sense to me.
You had similar things happening on the wizard side. In 1e, a magic-user got phantasmal force as a 3rd level spell, while it was a 1st level spell for illusionists. In 2e, it was just a 1st level spell.