I think a sense of humor is admirable in anybody, including politicians. Two of the most humorous ones: Bob Dole, and Mo Udall, both former members of the U. S. Congress.It also think Reagan and GWB have a good sense of humor and can laugh at themselves.
I haven't heard Al Gore at his humorous best, Jim, but those are certainly funny lines, I think.
I don't think it is so important that they write their own humor. Most comedians rely on others to supply them with jokes, including Bob Hope, Jay Leno, ...heck, I don't know any that don't. It's all in the delivery, anyway.
I had some contact with one of the the greatest comedian of all times: Jack Benny. I was with him for a week in preparation for a concert with our symphony orchestra. He was the most un-funny person off stage I've ever known.
DougR