"Goon Squad" is a good description. And yes, that is what people want. Video game necromancers generally summon a range of different, specialised undead, not just a horde of generic skeletons. And that's very much part of the fun. And the OP is right: there is absolutely no way you can do that and make it fun in a turn based tabletop game when you have five other players waiting to take their turn. The best you can do is design something that is okay when there are only one or two players.
Making them all the same or treating them as a swarm, are tricks a DM can use to make the game flow quickly when there are a large number of entities in play. But they are not fun for players. It doesn't give them the experience they are looking for. In Diablo Clone Last Epoch my necromancer has around 12 summons (not including short duration wraiths), including six different kinds of specialised skeletons. In the Lich path in Pathfinder: Wraith of the Righteous you get to replace your NPC companions with undead companions, as well as customise a pet skeleton, choosing its class, advancement path and gear.
"Lets have a zone spell that does damage and fluff it as undead" simply does not cut it.
Compromise is exactly what the WotC necromancer is. They even have a better compromise in the Reanimator, which, whilst limited to one pet, gives the all important customisation options.
Some things, you really can't do without a computer.