I agree that he isn't meta, perhaps he could get a small ult buff for a better mid game but for the most part he's fine. I say he's not meta because the meta is all about who screws over who's botlane first. champions that need 2-3 items like Azir to really start dealing damage, Nashor's void and deathcap, just can't compete as well against someone who needs 1-2 items morellos/ luden to blow up your adc botlane. Hell sometimes just base damage is enough for the 1 shot for some champions. But as champion himself, he's fine. Definitely a situational pick, you need a comp with tanks/cc to make him effective at dealing sustained AoE damage without much communication. You can't blind pick him every game like Orianna and ahri, and expect to do well.
Not being meta isn't really a reason to buff him though, Veigar isn't really meta atm, but who wants to buff a champion that can 1 shot you even sooner. I certainly don't.