Remathilis
Legend
]You summed it up perfectly and I do not see any problem at all with the selection except that I would make Templars Warlocks as I already posted a few times. I do not need Xanathars for DS. (Fun fact : are Beholders a thing at all for DS, do they exist there?)
Quite a few people here, many of whom are also in favor of curated lists, don't seem to agree. But that's the issue, isn't it? For the last half dozen or so pages, aside from fighter, rogue and wizard, nobody really seems to agree what else fit in Athas or how to mechanically represent that. There is little agreement if Templar is a cleric, warlock, NPC stat block, or what. Psionics is ping-ponging between reflavored magic and a whole new class. One person's acceptable class is another's non-starter. I don't think there is any other setting that has this much disagreement about what should or shouldn't be in it. (Well, maybe Greyhawk Grognards who don't believe anything added to the game after 1983 should be in it).
Look, what you do in your home game is up to you: ban everything but human champion fighters if you want. But the title of this thread asked what WotC should do, and there is no consensus on what WotC should limit beyond the canonically dead races and some obvious "cheat" spells and effects. So if WotC wants to cast the biggest net, it should make the most options available and let the DM ban to taste. It is consistent with what they've done with every other setting they did so far, including the mini settings with Greyhawk and Ravenloft in the modules.
This is they way.