Firstly, you are not the first person to say a this too me. Everyone I tell questions my motivations for it.
I think I like the idea of being able to make a difference from a high level. On that point, I would love to get into diplomatic politics. Meetings at the UN; that kind of stuff. Also, i agree with the fact that politics attracts the wrong type of people. In Australia, most of our politics are former lawyers. This frustrates me slightly. Being an engineer, the chance to bring a different line of thinking into the political debate is quite exciting. I think it does open you up to scrutiny but that just comes with being a public figure. Just need to be careful what you do.
It seems that in the US even the good people are vilified. You can be a decorated war veteran and get Swift Boated. Good luck, hope you have thick skin. I agree that having anything other than a lawyer would be a good thing. Diversity is a commonly bantered about term but it truly is important when it comes to ideas.