It comes down to proportions. Let's say 10% of widgets are awesome and the remaining 90% are not, regardless of colour. Per parent's post, let's assume 1/12 of the widgets are colourful. So now (rounded roughly):

  - 9,2% -- awesome, non-colourful
  - 0,8% -- awesome, colourful
  - 82% -- meh, non-colourful
  - 8% -- meh, colourful

If you're choosing freely, you'll (hopefully) end up with the awesome top 10% (1/12 of them being colourful). However, if you're forced to make 1/3 of your widgets colourful (and there's only 1/12 of them overall), you end up with:

  - 6,7% -- awesome, non-colourful
  - 0,8% -- awesome, colourful
  - 2,5% -- meh, colourful

The previously "excluded" (or rather, not promoted) group is exactly just as good as the rest, it's just not numerous enough -- if you want 1/3 of colourful widgets naturally (instead of the expected 1/12), their averages have to compete against the rest's best, and that's where the perceived inferiority comes from.