Yah a tank at least can hold their own for a little bit if they run in...a DPS...as a healer I'll just let a DPS who Leeroys die since if I hit them with a cure I'll take hate and wind up dead myself if the tank(s) aren't prepared. As a tank...I usually wind up reflexively grabbing the boss and trying to recover the attempt depending on the Trial. Running in with buffs isn't even that big a deal, but if the healer hasn't buffed you there's a chance they're not quite ready to start the encounter either. I'll happily buff after the pull, but it isn't my problem if you pull with no warning as soon as the barrier falls and I'm typing something quickly in FC chat or something and you die as I scramble to cancel out of the chat box and cure you.