I can only assume since it was phased out from 1994 onwards slowly but surely (don`t mention the plaza paving!) it was decided it was out of place at the entrance. Funny how what goes around comes around.
Regarding the 1997 photo, I`m afraid I do have an explanation. That is a MKIV monorail. The photo may be copyright 1997, but was taken in 1982. I`d say end of September. The sculpture was late in arriving at the park - it was in position just in time for the opening. A close look will show no American Gardens covered stage, now Showcase entrance stores, the Seas plot is still dirt, and that the Centorium extention isn`t built, further placing the photo to at least pre 1985.
As an addition, I wasn`t sure, but it looks like that is the Stargate Restaurant extention being built - something being done around September 1982. Any chance of a larger sized pic?