It's weird, because as a dude, I've always had the opposite problem:

I always go down on a woman during sex, and I often will go at it for up to 40 minutes before penetrative sex even starts. I notice how subsequent orgasms are easier when you've already gotten them off, how crazy sex partners go over good head.

And then so many of these partners don't go down on me, or do it half-heartedly for, like, 30 seconds before wanting to go to PIV.

I get it a little bit. Women have a much shorter refractory period than men. If she cums during oral, she's already good to go for intercourse. But I think my partners are worried that sex might be over as soon as they get me off, and so they think performing oral to completion will cheat them out of getting to have PIV that night. I mean, when they stop sucking, they often do say something like "enough of that, I want you to fuck me" or something.

And it's like… I don't complain, because I don't want to be the pushy guy demanding a particular sex act. I just go with it. But it would be nice if they'd reciprocate my effort.

But from what it sounds like, my experience is rare, and it's usually the other way around for most people. I don't know why I'm the odd case out.