I would have expected them to fire back up after Dawnguard released...

Perhaps once we get our hands on the source code for the new scripts. I would be very interested to see if the system they incorporated to handle Vampire Lord and Werewolf perk trees was modular, and that you could set up your own quest to track progress of custom events, and set up a custom tree!

That would certainly be a nice surprise...

People only come here when they problems with the CK really. Modders who don't have questions or problems tend to be active in Skyrim Mods forums instead of here, where they have their threads of their mods. So the amount of visitors on this forums is no representation of modding popularity.

Don't expect to be able to make new custom Perk trees, that stuff isn't handled in Papyrus scripts.