As a new guy here I guess I'll post my thoughts on this topic based on what I've noticed.
1) I suspect that many GCers don't even know that the Waymarking site exists. It's not as if there's a flashing banner saying Hey! want to see some cool things in your area? Find them on Waymarking! Personally I would never have found the Waymarking site if I weren't interested in learning how to find benchmarks.
2) The Waymarking site isn't as "user friendly", especially if you aren't a premium member. Here's an example: To go to a cache near my home I simply pull up the (fullsized) map and move it around to my area, find a cache and click on it, then download it straight to my gpsr. If I want to find a waymark site to visit I have to use the (little) map, then pick a category, sort by closest, then click on one that I want to go to. As I'm not a premium member I can't download any info to my device. I have to enter the info by hand. For me that's the big one, even as a basic member it's a one button operation to download basic cache info to device, here a basic member isn't a redheaded stepchild, he's an ugly third cousin.
3) I'm pretty okay with taking a pic as proof of visit. The requirement that you put down what you ate at a fast food place is pretty amusing, if I go to wendys can I just put the number 5 in the field? (I do like the son of baconator)
The upside is that I did put in my first waymark today, even though I went 0/4 on benchmarks I was able to log a small monument right in the middle of town that no one else had noticed. The downside is that one of the benchmarks I was looking for was supposed to be 6 inches from that monument