My guess to explain the drop would have been that there's so many questions already answered here that there's a reduced need to create more nodes! Yes, plenty of questions are asked over and over, but even I use the search functionality occasionally.
To get more top level nodes, just invite the maintainers of some modules to move their support forums from mailing lists to perlmonks.
- Specialized questions about specific modules are the ones that often go unanswered here anyway.
- It's a waste of energy to sign up for a mailing list just to ask one question about a module.
- Many module mailing lists are so lightly trafficked that it's sometimes hard to get an answer to a question. At perlmonks, you can at least get a educated guess from someone that might spark a new direction of thought.