Remathilis pretty much covered this but when i picked up 5e, the issue was that you literally couldn't kit your necromancer out with necromancy spells. 95%+ of your build was the exact same as every other wizard because there just wasn't enough to fill out the concept. There are a bunch of things like necromancer, elementalist, and summoner that deserve to get full class features instead of sharing the same spell list with every other wizard at the table.
I guess this goes to show that if you take 2 different DND players, you might get 2 completely diametrically opposed views on what is done well.
I'd much, much rather wizard subclasses work like this instead of the piddly school subclasses. Give necromancer a full kit of undead animation and spirit control. Give the illusionist a full set of illusion and sound manipulation. Give the summoner big, unique summons and a pet. Give the wizard subclasses special stuff instead of just letting the class be a pile of old tofu.