@jby perhaps one way to look at it is that the first time Trump was elected by a coalition of different voters with diverse interests, so the garbage he spewed back then was moderated by push and pull in different directions.

This time it seems to me like much of the coalition is absent, leaving Trump in an echo chamber without as much rhetorical challenge and (as seen here) fewer ideas to fewer ideas to regurgitate, so he has to return to the same line to fill the time.

GOP primary voters seem pretty insular this time, so I think you might be on to something.