As far as a positive portrayal of an engineer -- I think it kind of undercuts the message to have an actor take his place in the commercial.
The real inventors are not in the ads; they are played by actors. Mr. Bell said he wanted to ensure the commercials were humorous, and avoid arguments with Intel employees over which should be featured.
"When you are required politically to cast certain people and get everyone involved, you tend to get this watered-down, feel-good campaign that works really well internally and makes the company itself feel good," but does not appeal to consumers, he said.
http://www.nytimes.com/2009/05/06/business/media/06adco.html
For TV advertisements, you need people who can act. Engineers aren't actors. Save the real engineers for informational pieces like this interview.
Only B list celebrities play themselves on TV.
Then what is he doing on Conan?
"A decade ago, he would have been reduced to caricature" and the same thing happened now, so who knows whether the real Ajay would've been cool with it or able to pull it off. Consider all the wooden ads by sports stars that come off as stiff and rely on the recognition factor only.
USB certainly was a huge step and made them a lot of money, much of which Ajay is responsible for. This makes him a rock star.