I wouldn't say traditionally. I love old comics, and you go pre-WWII to the 60s, like most media back then, I'd argue the tone was pretty conservative (though granted, in accordance with various industry codes and laws of the time, so make of that what you will). Even during the wacky Silver Age, you still had some solid titles. These days, it really depends on the team behind the title, and characters like Captain America and The Punisher are ideological punching bags for writers looking to make a point.