I agree with Lin here, which is rare
Sniper was made to own PvM. You cannot stop them. As Krumb put it, any buff you give a monster to hurt Snipers is going to hurt other classes worse.
Defender? What about the poor Gunslingers who already have a hard time with some parts of item and monster trials? What will they do to overcome Defender?
Pneuma? What about all the other ranged skills that don't need a nerf?
As for giving mini bosses special abilities to make them harder to kill...I'm pretty sure the mini bosses in the monster trial are just the standard in-game mini bosses. That means that if you buff them you buff the real versions too, which doesn't seem right.
I'd be fine with ToH being a bit harder. As Lin said, the wing's are basically hax. People should have to work hard to get them.