For guys like Ryder, Evan Bourne, and Kofi, the phrase "too popular with the kids to turn to heel" is frustrating to me. Kofi Kingston is NOT nearly impactful enough to WWE revenues to worry about his position as good guy or bad guy. If turning him heel made his character more compelling, that's a bonus for the WWE.
For every new heel they create, thats an opportunity to plug someone else in as a face - and get those 'kids he's too popular with' to love the next bubbly midcarder act they feed us. If Kofi turned heel, they could have Cody Rhodes start 'doing his mustache dance' and taping mustaches onto little kids during his entrance. BAM. Problem solved, plus some.