There are quite a few players who do not care for exact percentages, but there are also the nerdy few of us who are number-crazy and would "do anything" to get a hold of the figures.
I guess since the numbers are available to the development team anyways and since posting them for public display indeeds adds value to a lot of players, it is a good way to do this.
Those who "don't care" still have the choice not to use it, just like any other feature.