The accident involved a worker who was painting on a roof near the skyway when the skyway was closed. When it began operating, a car hit into him and he fell.
The skyway at DL was already closed before the accident occurred at WDW, so although the accident might have been a factor in closing, it wasn't the factor.
Some of the other factors were:
- the ride could only operate in good weather. If it was rainy, too windy or there was any lightening nearby, it closed. So, between 1987, when we started to go to WDW and the year it closed, it was often not running when we were there.
- the ride was old and had a lot of pieces that had to be custom made if they broke. You can't just go to Home Depot to buy skyway parts.
- it was a slow loading, low capacity ride that had long waiting lines.
- it took a lot of CMs to run. There were about 5 at each of the boarding areas (Fantasyland and Tomorrowland) and another 2 at the area in Tomorrowland where the cable had sort of a jog and switched to an uphill part. There probably were also some controller CMs that you never saw. 
- the CMs at each station had to actually "catch" the gondolla for people to get on and off. After loading, the CMs had to give it a push to get it going again. My guess is that ride led to a lot of CM back and shoulder injuries.
So even though it was a neat ride, it had a lot going against it.