Plus the second fighting style is a nice touch, giving more real flexibility (and allowing a real shift in performance if a special magic item that doesn't fit the original style is found, or whatever).
You can waste it by using it on the wrong enemy. You might think this is the boss, but actually the boss is in the next room. Or you've heard that the boss is in the next room, so you save it now, only to find out the the boss is a push-over. Any decision that you make is a chance for you to be wrong, and introduces inefficiency into the system.Unless youre completely incompetent, you cant waste your Superiority Dice. They are guaranteed damage added on a hit or a free extra attack. This doesnt mean that the dice are good options or anything, it just means that the .5 star BM is all around better than the no-star Champion.
It's not free. You're stuck as a champion. The "waste" comes in the DPR comparison. The crit damage is more likely to be overkill and not contribute to DPR than the superiority die is. In other words if half your crits are wasted on overkill you are getting 2.5% more crit hits, not 5%. That is waste. Meanwhile if you don't make dumb decisions with your superiority dice, ever die will be having full effect, and there is no waste.Passive abilities are always on, and you can never waste them. You might think that a critical hit is "wasted" when you roll a 19 on a goblin who was going to die anyway, but there was no cost associated with that - it's entirely free - and you'll get another free critical hit if you happen to roll a 19 when it matters against the boss. The theoretical benefit of random effects may be less than the theoretical benefits of controlled effects, but inefficiency is a non-issue.
It's not wasted if it's free. It's literally impossible to waste an infinite resource. There's zero cost associated with rolling a critical hit. If there's a lot of overkill sometimes, then whatever, because you lose nothing from it. You'll still have unfettered access to that critical damage whenever you roll a 19 later on.The crit damage is more likely to be overkill and not contribute to DPR than the superiority die is. In other words if half your crits are wasted on overkill you are getting 2.5% more crit hits, not 5%. That is waste. Meanwhile if you don't make dumb decisions with your superiority dice, ever die will be having full effect, and there is no waste.