Honestly we should define 80% as the new "100%" on such batteries and label "charging to full" as "overcharging".

Psychologically, people understand charging a battery to "125%" (or whatever) a lot better: Do it when you really need to but if you do it all the time it wears down the battery a lot faster.

Yes and yes.

I recently investigated large portable power banks (Jackery, etc.) and like that there are options to charge faster with a battery life tradeoff. Let people make their own informed choices.