Compared to the impact they can have at their job (positive or negative), this just doesn't seem like a big deal to me. Obviously I'd prefer if they didn't do it, but I don't see why it needs to be a bigger issue.
Insider trading causes two problems:
* Undermines faith in, and thus reduces efficacy of, financial markets
* Reduces the overall returns for everyone else a bit
While it becomes a problem when rampant throughout the market, I don't think a few hundred members of congress would collectively have much impact here.
I'm also a little wary of the kind of person who's willing to go into politics and isn't in it for the money. While there are a handful of truly dedicated public servants, most people who aren't in it for the money are either extreme ideologues or power hungry narcissists. I'll take a politician who's mildly financially corrupt over someone who wants to abolish either taxes or private property, and way over one who wants to become a dictator.