The reason for that is at the time it was felt Disneyland needed to have something of interest to excite current Park goers.
The Disney Company, particularly in the early 80s, was not the powerhouse it is today as far as contemporary cultural impact.
It was looked upon as old fashioned, and something only little kids and crusty old folks could enjoy.
There was a gap there in the entertainment offerings - very little appealed to the older kids, teens, and young adults and it was felt that needed to be remedied.
At that time ( mid-80s ) the feeling was that Disneyland was becoming a bit of a relic and needed to have something to excite the younger generation of Park goers.
Tony felt strongly about that aspect - having a good mix of Attractions that appealed to all audiences, as well as have more contemporary offerings to excite the newer generation of Park visitors.
There was nothing doing so at that time within Disney's own self owned IP collection.
So the decision was made to bring in creative film makers ( George Lucas ) and talented entertainers ( Michael Jackson ) and work with them to create new experiences that could liven things up a bit.
And boy did they ever.
'Captain EO' came first, then 'Star Tours', both of which were sensations when they first opened and became Guest favorites well afterwards.
-