Because we Citizens need ways to evaluate the people who are running for office to decide which one you want to give her a vote to.
You've had plenty of time to do so for both candidates, as both have recently held office.
Name one presidential election cycle where no debates were done in modern times.
This is moving the goal posts, and a bad way to evaluate the necessity of a given debate.
It would be immoral for someone running for office to not put themselves up for evaluation via debates. No one is owed blind loyalty.
I'm not suggesting blind loyalty. It just seems odd that you're trying to say the public won't have a chance to evaluate the options when that clearly isn't the case. Trump held office from 2016 to 2020, Biden from 2020 to 2024.
If anybody doesn't already know what these guys are about, then a debate won't solve that, as they already pay too little attention.
And besides that, the immorality of platforming insurectionists far outweighs whatever immorality could arrive in the form your suggesting.