Historically speaking, the game was always an interleague game, though that changed once interleague play ceased to be so special. Attendance and interest on the part of fans doesn't seem to be the problem here, however. This is a matter of scheduling and flights and stuff for current players. Though I sort of wish they'd keep it up -- maybe I'd go some year! -- I can understand why they don't want to.
A history of the game can be found here.