Trump NOT debating should raise questions in everyone's minds. Regardless of the videos that he's made, the tweets and the rallies, that is not the same as actually going up against his opponents on a debate stage.
People don't want to see theatrics, they want to hear what each candidate is going to do on specific issues. DeSantis, Haley, Scott, Pence, and Christie all have some sort of record. Trump has his record as president and Ramsy, well, he has none.
IMHO Trump has been slinging mud at DeSantis even before DeSantis decided to run and is terrified of debating him. DeSantis is more calm, more capable and more accomplished. Unfortunately a lot of things Trump tried to implement disappeared as soon as Joe took office, so what he did was in essence ineffective.