I think the science actually supports this. Studies have shown leftists tend to be more self-critical and are concerned for the nuances - the "shades of grey". So their memes must cover more angles of an argument to be effective. Right-wing are more black and white thinking, and don't question themselves once they make a decision. So their meme's are straight to the point and simple (and usually so full of logic holes and lacking in comedy that leftists say: "the right can't meme").

I'm gonna get vilified for this, but do you mean one side makes memes with sharp commentary and the other makes memes for dumb people?

probably because the right lack reading comprehension :)

edit: fix typo