The official rule is NO TAPE period. KS has agreed as a officials group that you can tape the straps, but not the sides/ears. Not sure how this will follow kids wrestling. Beeson is correct, at it's core it's all about money to sell more headgear.
The official justification is part of what Hotrodder54 said and part because they said the tape over time is uncleaned and carries germs...No more than tape on shoes or about 95% of all of the disgusting kneepads out there.
So for now, you can tape the straps, but not the rest. I am sure there will be several different judgements on this over time.