From my research over the last week or so trying to work out a few new EP's for my two new scopes, I think it has more to do with low magnification and wider AFOV. Once upon a time you could only get a 40mm with say 45d AFOV and that would be fine in a 1.25" EP. Now with 100d AFOV I think you can get a 2" EP at say 18mm to give a similar TFOV.
Hope that reads how I thunk it
cheers