My guess? Marvel got a taste of what was later to come with Dan Didio. Inmates got to run the asylum, but first had to deal with all the stories and character development that happened after their preferred era's status quo but before they got to the level where they were in charge, and chose the path of sabotaging and destroying whatever they either didn't like or viewed as getting in the way of telling the stories they wanted with the status quo they wanted. Of course, this is an extreme oversimplification, but I've been reading stuff from the big two for nearly 40 years now (yikes!), and "Destroying whatever I have to or flat out don't like to get the status quo I want to start off with" seems to be more creators' preference than not.