Yeah, I got that. But the Disadvantage is only against you. Which means that if you don't have Warcaster it's mostly only useful if you've got undead using a ranged attack specifically against you. Since most ranged undead will be intelligent, they'll probably pick another target, so I suppose in that edge case it would be useful. But...again, without Warcaster...not useful enough.
True, I forgot to mention that I'm going through as a Necromancer and just eat the disadvantage because most undead at low levels are ridiculously easy to hit.
But yes, at higher levels it will lose its luster sadly.