that you should keep up at least a little with politics and get an informed opinion.

But even if you don't want to do that, one could argue you should still vote even with very superficial motivations, so as to do your part in getting the atrocious voting numbers back up, and counter the trend where increasingly the politicans care only about playing to their base (and to lobbyists), because the other side's base hates them anyway, and the centre doesn't bother to vote.

Of course, in any case, one person not voting won't make any difference whatsoever, so a cynic would argue that it doesn't matter what you do, and you'd only be trying to make yourself feel good by linking any positive (or negative) consequences to your failure to vote.

I wouldn't overestimate the "knowledge" of the average voter. And even among those who are supremely knowledgeable, particularly in a two-party-system like the US where you generally have precisely two choices or not even that, all that knowledge won't necessarily do them much good - they still have to pick one side or the other, even if they figure both pretty much suck, and take the good with the bad.

The polarization also has the consequence that politicians have fewer and fewer space to walk their own path and make their own calls - it's only logical that the individual characteristics of even Senate candidates are growing increasingly irrelevant, with a lot of voters looking only at his or her party tag, so that means your lack of research into candidates is less of a problem as well.