–…concluding that “Basically, Game X is better than Game Y” because of an arbitrary scoring scheme doesn’t benefit the reader.–

I believe that this is the reason for assigning the scores in the first place. Sure the score is subjective, but if I want to know weather to get Killsome 2, or Haze, which are very similar games, a quick comparison of the score can tell me which one I am more likely to enjoy.
Otherwise, I would need to read a complete review of the two games, plus reviews of every other FPS available, rather than just saying “I will get the one that the reviewer regards the best via his numerical score”
A good compromise is a 3 to 5 star system. That way, you CAN generalize poor and good games, but also allow room in the review for discussing the subjective elements.
For example, I would buy a 3/5 star Hardcore PC sim over a 5/5 star arcade racer, because I enjoy Sim racing much more, but the majority of people (Who the review is written for) would probably enjoy the 5/5 arcade racer more.