The ground that Magic Mushroom runs through is very wet. The trail there got pretty badly mangled over the winter so it became necessary to do quite a lot of maintenance. Given the expense and effort that rebuilding trails requires it’s not surprising that the FC decided to do a thorough job.
I expect that the cartwheel corner will wear in soon enough and its roots will reappear but it had obviously become too eroded for most riders (I of course cannot comment about the abilities of Glentress Gods such as yourselves). That was plainly obvious from the number of shortcuts that had started to appear near it.
I think we perhaps should also consider that these red graded trails were graded red when they were built, not after several years of hard use and erosion. Perhaps they’re not being dumbed-down to a sub-red grade but are being brought back to what red grade was originally considered to be?