Problem with this thread is twofold:
(1) Illusion Control as a whole is easily one of the best powersets in the game, and it could easily be considered to be in “Should not be buffed under any circumstances” territory as a result.
(2) The sub-issue of Knockback has obviously been dealt with over and over on this forum, and, until the developers signal a major shift in their thinking, we have already established that “Slot a Sudden Acceleration Proc” is the appropriate way to address any player’s aversion to Knockback.
That being said, it sounds like there is room for improvements to the Phantasm’s AI, which I would certainly support.