I've been sinking a lot of time into Virt-a-mate/VaMX. Just as @justsomedude101 mentioned, it's a really steep curve to get something out of it, but I've enjoyed it a lot.
Immersion is incredibly powerful because of 6-DoF (video can only approximate), and even voice control for interactivity. (Just say "I'm cumming" rather than play target practice to hit the right button.)
Many creations in VaM are as you describe, plain pick-the-position scenes, with no "game" to it. Out of dissatisfaction, I'm making something with story, choices and (limited) reactivity. Which is also an advantage since you can make the exact content you want to see - if you have the time to waste.
On topic: Games on SLR could be neat, but seems extremely costly to develop? Passthrough would be a valuable feature.