That is the point, and that is why it is being used. For a given number of subpixels (max that fit in a specific screen) pentile is better. Of course if tomorrow someone manages to fit 50% more subpixels in the same space and decides to go rgb the result will be better. But with 50% more subpixels it would be better to go pentile again with 50% higher resolution. Chicken and egg

(for a direct comparison compare an E7 with an OG Galaxy S)
WVGA pentile is better than nHD rgb.