compared to most event eidolons being around 2k atk? even 500 atk less isn't that much of an "immense loss" unless you start factoring in assault values and buffs...
What is the reason to not factor in assault and buffs when they are always there and play a huge role? Also let's not forget that 15% ele buff isn't equal 15% dmg boost, since it is on top of at least 80% from main and support eido plus 45% from elemetal advantage.

now we all agree on the fact that as a main eidolon, they are really horrible. but as a sub, they do have SOME use UNTIL YOU GET BETTER STUFF.

so i'll say it again, IGNORE THIS WHEN YOU HAVE BETTER STUFF. until then, use them.
The same can be said for everything in this game, problem is: most stuff in this game is better than Lilim, so that SOME USE it very abysmal