I actually think there’s a lot more quirky subtext in older stuff, especially when the Hayes Code was in place. I think the big difference now is that the quirky subtext isn’t nearly as sub, they really want to make sure you notice how subtle and quirky they are. In the old days they were trying to sneak stuff past censors and studio heads so it was a lot more subtle.
I’m pretty well-versed in pre-code fare (heck, I’ve seen every Wheeler and Woolsey movie, for example... and a film of theirs like “So This is Africa” is indeed brimming with innuendos and endless other cultural references... very akin to the modern spoof genre).
I’m getting at something beyond that, in terms of all dialogue, spread throughout every genre. It might even be related to the aspect of over-direction in films, in which so many filmmaking techniques are overused, bringing a self-conscious attention to themselves.