I think you need a better definition of ‘Renaissance Man’. I don’t think it’s enough to just be relatively accomplished in several different disciplines. I think you have to make significant contributions to several fields.
For example, take Richard Feynman. Sure, he was a physicist who also cracked safes and played the bongos. But was he a world-class bongo player? Did he discover new techniques for safe cracking that are used today?
By the standard of, “really smart guys who do lots of things”, I’m guessing half the people on this board are ‘renaissance men’. Most smart people do a lot of things. It’s not uncommon for brilliant people to dabble in painting, for example. But how many physicists have paintings in the Louvre?
Leonardo is always presented as the prototypical example of the Renaissance man. He created some of the greatest paintings in the history of man. He also made tremendous discoveries in anatomy. He built the first robot, and the first armored tank. He was employed as a military engineer, and made significant discoveries in the nature of flight, including a design for a hang glider that would have flown had he built it.
By comparison, most of the contemporary ‘Renaissance men’ just don’t measure up. Ben Stein is a smart guy, but he’s a mediocre actor, and his ‘comedian/game show host’ schtick is really just parlaying his personality into a bit of fame. He’s basically a guy with a good education who’s a good writer and has a unique enough personality to make him stand out a bit in entertainment.
And while Asimov was a very prolific writer and wrote on numerous subjects, he never made significant contributions to any of those fields, and his wide-ranging subject matter may just be due to being a workaholic with good research skills.
I think the problem today is that it just takes too long to learn enough about any modern field of science to be able to contribute significantly to more than one or two. The fields have become too arcane and require too much specialized knowledge. In Leonardo’s day, a man of insight could make breakthroughs in many fields, simply because there was a lot of basic knowledge which had yet to be discovered. And a fundamental insight could lead to breakthroughs in multiple fields.