The "click page number" to see more posts is a really out-dated navigation model. While we don't necessarily need infinite scrolling, like discourse.org, even a link at the bottom to "show more posts" or "go to next page" would be significantly better than what we have today.

I agree.

Perhaps even being able to choose, in profile, how many topics to show at a time? DeviantArt does a similar thing.

Would it be a hard thing to implement?

Not hard things to add, just require time. We'll be improving this as per your suggestions and our own ideas soon. We just put in the simplest thing with required functionality as a first pass.

As for infinite scrolling, it always feels flaky to me. I'll have to experiment and see if I can make a non-flaky user experience for that.

I've added prev/next buttons on the ends of the pagination, as a stopgap.