Lilims have a plethora of problems, yeah.
1. 90% sounds high, but since it only applies to three out of five members, you should think of it as 54%.
2. It's Character attack, so you need to use an Elemental Eidolon as your secondary. And oh look, the secondary Eidolon also only applies to three characters, so your damage output is gimped.
3. Because you're using Lilim + Elemental, you don't have any +HP Eidolons, lowering your survival ability.
4. Your team is unreliable - if anyone dies, you either risk losing one third of your damage output or de-activating one of your Eidolons.
5. Lilims have low base attack.

There are extreme cases where a Lilim can be good for you, but these extreme cases require you to have some extra ordinary off-Element Hime. Plus it needs to be in a team where you have little investment in skill levels, since if you have proper weapons, other Eidolons will just be better. As such, ultimately you'll just never, ever use Lilims endgame.