Vicious rumour is that a letter change from E to C over D is politically untenable (constitutes a recognition that it was never that good an idea and all that).
E F180 to F245 is being maintained because of the 3 or so VFRs that can get up that high who are demanding that their right to do so without talking to anyone must not be infringed!!!
The idea that the majority of IFRs like it that way is demonstrably untrue- maybe it would be different if the E procedures weren't so crap.