The problem is his tactics. And the other problem is that he's proven that HE is not willing to accept the outcome. You do realize that that he is threatening to destroy the democracy. The stakes are too high.
Anybody who thinks that he wouldn't destroy the democracy is kidding themselves.
I actually have a great deal of sympathy for your argument, but let the voter's decide is also a very compelling argument. Otherwise you go back to a 19th century America where the party establishment decides who runs and doesn't run. Strangely as I wrote that, I realized that might be the Canadian method. I'm not criticizing, but Americans like the idea of a direct vote for our leader and outsiders shaking the political establishment up.
Which leads to me a very important point. I wish we could go back to 2017 when the Democrats started to lose their mind and began using legal apparatus to intimidate and dog Trump for four years. It angered a lot of Americans more than it really accomplished.
If you are worrying about Trump "the dictator", let's look at what happen during his first term. He didn't get everything he wanted even when the Republicans controlled Congress the first two years. We have liberal members here consistently make the contradictory argument that Trump didn't do anything as President while calling him a dictator. There is also the recalcitrant Federal bureaucracy. It's very hard to change its course. It just is.
I don't know if you are a student of history, but I think it's fairly safe to say that "dictators" are very good at getting things done whether one likes the actions or not.