I don’t know Jimmy Fallon, but back when I had the ability to watch his show I did occasionally. It was light and easy to fall asleep to, but interesting enough to entertain if I had trouble doing so. I think all the late night shows to some degree understand this is their audience, and Fallon’s was especially good at keeping it inoffensive.
If I were watching it midday or in the evening, I’m sure I’d find it less valuable but as a late-night show, it foots the bill well. I don’t know the truth of this matter, but I hate it for him if he’s struggling personally and adversely affecting those who work for him.