I think the most legit objection to my* modest proposal to quantify every single subjective aspect of sports is that it might take some of the fun out of watching. When a football fan looks up Brett Favre's career INT stats, the fan "knows" something that the stats can't tell that has some value in predicting Favre's future and analyzing his past. With this rating system, that knowledge would basically already be a part of his expected value stats, and the fan would have no such "insider" info. And the better the rating system is, the less insider info fans can expect to have.
To the extent that the fun of watching sports comes from thinking you might know more about what will happen than everyone else does (see: the profligate amount of sports gambling, fantasy sports, etc.), it's possible that quantifying player's value like Bill James overdosing on adderall really would make sports less fun to watch. This is possibly related but not exactly the same as why expected value poker would be less fun to play. There is a degree to which the variance in the outcome of a given event is what makes it exciting to watch.
* I hesitate to call it "mine" because I'm willing to be that I'm not the first to have thought of this idea and I'm probably not even the first to write about it, although FWIW I couldn't find anything on a quick Google search.
Today and tomorrow are the best two sports days of the year. You can quantify your degree of manliness by looking at the highest regional seed you have advancing to the final four:
Only 1 seeds: Welcome Christiano Ronaldo to AMTB! Who knew you had such a refined taste for psychology and statistics?
Highest is a 2 seed: Why do you even bother pretending to shave in the morning?
Highest is a 3 seed: Your favorite video game is probably Super Princess Peach.
Highest is a 4 / 5 seed: You probably prefer smooth to crunchy peanut butter.
Highest is a 6 / 7 seed: No one is going to call you out for this... to your face.
Highest is a 8 / 9 seed: OK in my book.
Highest is a 10 seed +: Welcome to the upper echelon of manliness. Drink it in... it always goes down smooth.