I've wondered that as well.
I think maybe more preachy. When I look at some of the older comedy shows I used to like, they pretty much hold up, and I find the left-wing comedians in them are giving it to all political stripes and ideas.
Not now, even with the same shows and comics.
What I am not sure of is where conservative comedy, or right wing comedy, is these days. There certainly seem to be some elements of the right wing that are much more intellectually critical and lacking in be nice, which is usually a better starting place for comedy.
I do think that most second rate comedians may be smug, whatever their politics. It's a rare few who are so iconoclastic they take on everyone. In a way it's like the very best journalists - they tend not to be joiners, and when they do join it's very much on their own terms.