Keep Irelia Disarm

Irelia's disarm may have been situational (it requiring someone to back into the walls of the ult to proc it), but it was a defining and even important feature of her ult. She is the only champ with a disarm that is _only _ a disarm, the other one being ult which roots and disarms. Why remove such a significant part of her ult? It's significant in the sense they advertised this when she was being reworked. But now they're just cutting it out? Why not reduce the slow to 75% and just keep the disarm on a duration that is the same as her ult at all ranks 2.5 seconds?