I don’t think it needs a huge buff, but reliably two-shotting Crushers and Maulers would be neat.
Even… THEMSELVES! 
I would see it as a buff if both BB and KF could only target taggable enemies.
The first to stop pugs from using it on poxwalkers and the second to “save” it for useful targets.
Like a revolver.
Revolvers and krak grenades can. Hell even plasma can I think.
I’m not sure if revolver/plasma still can without using executioner’s stance and krak grenades are extremely limited without taking both grenade regen talents
also, technically, you can actually achieve one shot kills with brain burst on crushers with scrier’s gaze, precognition and empowered psionics, it is very fun if you manage to get them all running at once because you can just sit in the back brain popping crushers rapid fire.
also i can confirm that being able to one tap crushers with brain burst is insanely strong because even having it powered up for 10 seconds let me completely annihilate incoming armoured groups
Was playing Psyker the other day and I generally found it useful to get those targets that were out of reach or in a blind spot for that particular pub team composition that nobody else was focusing on. As ppl have already said, its a tool, not a main weapon.
Sure, you can use it as a main, but if everything is being destroyed before you can brain burst it, then you are focusing, imo, on the wrong thing the team needs. Why would I bother trying to compete with a competent Vet who is taking all ranged targets out?! Thats some weird psychology right there!
My philosophy is find my niche in whatever team Im in and fill that role as best I can. Some games I didnt even pull my BB out and just melee’d everything or flamed hordes or force sworded elites etc.
But then again, I dont mind not being the Hero that pulls the entire team to victory and sometimes just being a good cog in a machine satisfies me well enough.
I use psyker with BB, and I think oneshotting ogryns would be OP.
I could agree if we are talking about human-sized enemies (scab ragers currently survive BB, dreg ragers don’t)
Being a psyker in a team full of vets when you have brain burst? You honestly think you can’t compete. And that’s not cool. It sucks for psykers to go from 0 to 100 peril without being able to land a single brian burst. I think it should be competitive.
Isnt that like saying: “Why cant I compete with a full team of psykers running flamer staffs on crowd control while Im using my Power Sword, all the enemies die as Im swinging on them.” ?
At that point I would stop trying to “compete” and fill another niche.
And this is why I have multiple loadouts. With the basic QOL addition of ‘here’s all the weapons the team is using’, I can spec into horde, elite, all-rounder, support, etc with the click of a button.
Im lazy, so I just all rounder on most characters. Its actually why I dont like taking a flamer on my zealot, I dont like not having something to take snipers etc. Maybe if I had premades I would or sometimes if Im feeling particularly adventurous.