I think there's some truth to the idea that they don't go for center right because they promise to do nothing useful for their voters.

My take is its less left/right and more useful/useless. Obama won big because people thought he'd do something.

Trump promised a lot of change and boy he's certainly doing exactly that.

At the end of the day though, I think the time of party politics is over. Whatever Americas gonna be like next its not gonna be this

The reason people didn't vote for these two had little to do with being "center-right". Both of them were very unpopular before they were forced as candidate undemocratically. Democrats would have won with Bernie and their chances in 2024 would have been a lot better if they did a primary to pick a candidate people actually like and want to vote for. Using an candidate people hate will work if the party is far ahead in the poll, not when it's 50/50.

The left/right divide in American politics is a myth. Clinton and Harris are both establishment candidates. The only establishment candidate to have won a presidential election since George Bush Sr. in 1988 is Biden. And that was only because of Trump's first term, and he was losing his election before bowing out.

The Democratic Party has been putting forward establishment candidates since at least Jimmy Carter, the only exceptions being Bill Clinton and Obama. And notably, they both were, like Trump, a bit of a black swan in party politics.