Using maximum hit points shifts power from resource-limited (e.g. spellcasters, monks, etc.) to the fighter and rogue. With maximum hit points in use, fireball doesn't go as far, those ki points for flurry of attacks mean less and less, and so forth. This isn't necessarily a bad thing, but something to be cognizant of. I personally wouldn't do it and am unsure if I'd enjoy it as a player, but that's just my personal opinion; there's now "right" way to play.