I believe this feature was put in for the following reasons:

-To let you know this mob has gear, the gear is just over limit
-To keep things consistent with mob descs

As a tradeoff for letting explorers know that the gear does in fact come from this mob:

-Mobs will use this illusory gear to fuck your shit up, making for a far harder fight in many cases.

tl;dr, I dont think they're going to change illusory items, as their fucking you up is an intentional tradeoff.