Maybe it's the same where you live, but I've noticed a curious phenomenon on Southern California freeways: an almost complete avoidance of the rightmost lanes. This results in traffic patterns that are, to put it mildly, weird, and leftmost lanes that don't act the way they should.
In theory, the rightmost lane on a freeway is for the slower drivers, and the leftmost lane is for the faster. Even then, the leftmost lane, theoretically, is to be used only for passing. This is the theory whether you have a four-lane freeway out in BFN or a twelve-lane freeway going through or around a major urban area.
In practice, however, drivers tend to drift to the leftmost lane and stay there, even if they're gettig in other drivers' way. This results in a traffic pattern exactly opposite of freeway planners' intentions: the left lane jammed up with closely-spaced cars, most of which are going slower than they would like, and rightmost lanes that are almost free of vehicles. Madness! I have frequently found myself driving in the rightmost lane of certain strecthes of I-5 going significantly faster--and more safely--than the line of drivers caught in the leftmost lane, just because the rightmost lane was hardly occupied.
I think some of this has to do with psychology. Americans don't like to think of themselves as sedate, not with Fast And Furious 12 about to open up somewhere this weekend. We also have a youth-oriented culture, so perhaps anything that seems slow reeks of an out-of favor elderly. Whatever.
There may also be a matter of defiance involved. Frequently traffic is moving at well above the speed limit, and some drivers might feel like everyone else is "wrong" to go faster, so they don't feel obligated to move out of the left lane.
Some obviously has to do with cluelessness. There are a lot of drivers on the road that seem only dimly aware of other drivers or the rules and expectations of the road.
Look, whatever the reason, if you want to go slow relative to the rest of traffic, that's fine! You have every right to do so. But be aware of the traffic around you. If people are passing you on the right, that's an indication that you're in the wrong lane, and you should move to the right. Keep moving to the right until people don't pass you on the right anymore. It's not just a matter of courtesy (and it IS a courtesy); it's a matter of safety, yours and that of the drivers around you. No one will think less of you, and others will certainly appreciate the gesture.
And that's another way to be a better driver.