​"Halt and confuse ucode" had a lot to do with it IMO.

FYI: The 60 set the record of going from production to "traditional products" faster than​ anything else in DEC's history.     As I understand it, the 11/60 was expected to a business system and run RSTS.  Why the WCS was put in, I never understood, other than I expect the price of static RAM had finally dropped and DEC was buying it in huge quantities for the Vaxen.  The argument was that they could update the ucode cheaply in the field (which to my knowledge the never did).   But I asked that question many years ago to one of the HW manager, who explained to me that it was felt separate I/D was not needed for the targeted market and would have somehow increased cost.   I don't understand why it would have cost any more but I guess it was late.