I think maybe there should be alternate score modes. For instance, killing all the monsters would be an option, but perhaps killing none of the monsters would also be a challenge (maybe not with the current group, but in the long term). You don't want everything to be bundled together because then it is just a question of min-maxing what the best strategy is for points, and you'll end up with everyone doing speed for example. Of course, you can still get things like killing all the monsters in as few turns as possible, so perhaps the key is just to balance the scoring system adequately.