I believe that the Expertise feats were made for these cases...
That example is way too skewed.
In reality, what will happen at epic level is that instead of "two characters that hit same level average enemies on a 12, one who hits those same enemies on a 13, and two who hit the same enemies on a 14", it will become "two characters that hit same level average enemies on a 9, one who hits those same enemies on a 10, and two who hit the same enemies on a 11" because all 5 PCs will take the feat.
These feats have nothing to do with sub-optimal PCs (who tend to be sub-optimal for a total of 1) and instead have to do with the -4 math bug at Epic level.