We all have to think back to the 80's when EuroDisney was being planned. England was considered too wet and cold (and across a body of water that did not yet have a Chunnel).
Italy was slow, late, and not known for workmanship and hospitality. It was also known for crime, including thefts from tourists.
Spain had not yet had the Olympics, which was in 1992, and whichthen elevated the status of Barcelona rather dramatically. Back in the 80's, Spain was known for bullfighting and a dictator named Franco. Spain was also considered at the time to be a wonderful place to get mugged and beaten.
Overall, France was seen as the right compromise at the time, but indeed it was a compromise: Pretty good weather but not great, advanced infrastructure(with they say the best train and subway system in Europe), close to a huge tourist destination of Paris, a pretty good work force (although not overly friendly), and relatively low crime rate against tourists. Compromise, but in hindsight Barcelona probably would have been better.