I think that Kakashi not using genjutsu on a regularly basis is a big PIS.
Kakashi was praised more times than you can count for his ability to master the sharingan even though he is not an Uchiha. More than that, he is a Mangekyou user. Deidara was telling himself that he is shocked someone can use sharingan on Itachi's level.
We know that Itachi's main form of combat was using genjutsu so he is one of the best at it, but Sasuke, who is not relying that much on it, still used genjutsu at least once in every fight he ever took part in Shippuden.
It makes no sense for Kakashi, who is a prodigy and who was hyped everytime for being one of the best strategists, to not profit from the advantage that sharingan genjutsu offers.
Kakashi was praised more times than you can count for his ability to master the sharingan even though he is not an Uchiha. More than that, he is a Mangekyou user. Deidara was telling himself that he is shocked someone can use sharingan on Itachi's level.
We know that Itachi's main form of combat was using genjutsu so he is one of the best at it, but Sasuke, who is not relying that much on it, still used genjutsu at least once in every fight he ever took part in Shippuden.
It makes no sense for Kakashi, who is a prodigy and who was hyped everytime for being one of the best strategists, to not profit from the advantage that sharingan genjutsu offers.