This post should maybe be called: I wanna like psykers but don't.
Everyone knows that I play chaos space marines. A lot of my brothers and sisters in chaos like to take gift of mutation on champions. Not this gal! Not only am I am cheap with points (minimal upgrades) but I do not like spending points on something that is not a sure thing. Sure your champion might become a daemon prince, but he also might get absolute garbage.
So how does this relate to psykers? Well I see psykers the same way. I'm paying for mastery levels that MIGHT be useful? Nope. I'm going to use those 75 points from 3 mastery levels to get myself a vindicator instead. I will always choose more dakka.
There is just too much left to chance for me to get behind psykers. If it was just the dice rolling to get your powers off I could understand, but then the chance of just completely losing my 260 point daemon prince through perils? I would flip the game table in a hissy fit of volcanic proportion.
So take a cheaper psyker you say. Yeah okay, but every point matters to me and my cheapo tendencies don't want an HQ model that is so specialized for one phase. Maybe I'm being closed minded, but hey at least you know that if you ever play me I don't have many dice to deny the witch.