>>23443934
When you're trying to break into an (at the time) unestablished market, you don't want to be showing off your older wares, you want to be showing off your newer ones. Stuff like Wing and 8th MS Team ran circles around the older animation.
I would also like to add that Dragon Ball was straight up just not anywhere as popular as Z or even GT in America, which is a notable outlier in the popularity of that franchise. Take that as you will.