Could be because nobody is getting rich making them or pissed because they are not masters yet, or both.
Not likely. No one will or has ever gotten rich from making IP or WB. They are mostly made for personal enjoyment and some extra cash in the pocket.
There is no one on here at the present that being a Master or not has anything to do with additional IP. There are just no active skinners to make IP except for one left that does actually make them but they aren't free.
How many people making WindowBlinds left. 5 or 6. Use to be 20 or more. WE do it because we still enjoy it. I have offered to work with people to make an entire new WB. Seems no one wants to learn how anymore. The key word here is "wants". People want but no one wants to learn to make stuff. I would love to see more things uploaded. Keep the faith maybe some skinners will show up.