True, but Truman had served almost eight years. And if Truman had run, it would have been much tougher on Eisenhower. One huge difference is that was that had been five Democrats terms in a row. It's hard to keep building on that.
Their is no way Wilson could have run in 1920, given his health. He was bedridden, and not completely there mentally, and it came out in early 1920. It would basically been Edith running.
The one you left out is Calvin Coolidge. He could have easily won in 1928, but he spent ten years in D.C. and was sick of it. I don't think any president of the media era would give up power that easily, except maybe Reagan.
Coolidge was smart not to run for another term. He missed having to deal with the stock market crash of October 1929. But maybe he would have handled it better than the Progressive Republican Herbert Hoover did. He died on Jan. 5, 1933, so he would have died in office if he had been re-elected in 1928...but maybe would have died earlier if subject to the stresses of office.
Also his son had died young from a freak infection which must have affected how he felt about living in the White House.