Ake,
Yes, Biden and Obama are both Democratic Senators who have studied and practiced law. (Once again, the adjectival form is "Democratic," not "Democrat.")
Joke all you want, but having a doctorate in law, including Constitutional law, is an important asset for someone in either the legislative or judicial branch of government -- and it's kind of important for those in the executive branch to know a good deal about the law too.

If you're going to diss all lawyers, you'd have to put down most of our best Presidents and all of our judges.   If you think having a background in sports journalism or having been a relatively low-level military officer is better qualification, I'd say you don't understand what being the chief executive demands.