I play in explorer mode. I guess I'm just not very tactically-minded. *shrug*
There will always be a minority of people that are not interested by the tactical aspect and play the game for role-playing purposes or "just for the story".
I don't expect the design of game mechanics to be focused on catering to that sort of player however.
Glass Cannon is a high-risk/high-reward talent, which synergizes particularly well with Adrenaline, Flesh Sacrifice and other AP-giving talents.
It is balanced for the harder difficulties and is not only viable in explorer, regardless of what the original poster claimed.