Naah, most of the times its that management doesn't want to pay the migration cost. They will keep using a system till it stops producing value, or till adding new things is profitable. They can't give a damn about day to day or what's cool/elegant/maintainable because they don't interact with the innards, ever. These decisions are made with a single equation, if migration cost > new feature cost + maintenance, they don't want to migrate.

Edit: The maintenance isn't a long term view btw. They are not looking at a 5-6 year window where the migration cost slowly pays off. They are worried about optimizing the next quarter.