Why don't more people like us (for some conception of "us" that may or may not be coherent) stand for public office?

Because it's unpleasant and not very productive.

If you have any desire for privacy, you would (or should) hesitate to stand for public office for obvious reasons. If you have unconventional views, they are likely to be a problem, you will have to explain and defend them (or hide them). In general, (some) people will be mean to you, including being maliciously mean to you because you're of the enemy tribe and should be trampled into the mud.

And that's just the election part. Provided you made it through, you're likely to find out that the actual power you wield is pretty puny and your role is more akin to that of a cog in a bureaucratic machine. If your positions are sufficiently different from the usual ones, you'll often find yourself in the minory, unable to do anything. You'll face pressure to compromise, to deal, to conform.

Now, if by nature you like the political hustle and bustle, give and take, push and pull, that all is going to be fine. But people "like us" don't.