And the main reason was because the guy was genuinely funny, understood comedy, and was as happy to be the butt of a joke as to deliver a punchline.
I also saw a video of Foster Brooks roasting Jack Benny, and Benny couldn't help but laugh, laugh, and laugh some more.
I enjoyed Dean Martin and George Gobel.
Another insight was from What's My Line, the game show where the celebrity panel was blindfolded and Benny signed in as Heifitz.
And while Jack Benny could deadpan a gag, usually he was on the receiving end of it, a few shows could give you insight into how much he enjoyed comedy, his show, and perhaps comedy in general.