Paris is also at the crossroads of multiple access points from all over Europe. You can board a rapid train in London or Brussels and go directly to DLP. If coming by plane, you have both an international or European airport less than an hour drive away. At the time, low-cost airlines were not a thing, but they now allow people from all over to get there for a long weekend.
Also, the incentives mentioned by PP were linked with the fact that France wanted to develop the eastern side of Paris, where there was a lot of available land to build on - something needed by Disney after the mistake Walt made in California - and a massive single-site employer was the easiest way to kickstart that development. The entire town of Marne-La-Vallée was created for that purpose.
Finally, younger people might not remember why, but in the early 90’s, France was seen as the only really stable democracy (for a country with the proper size) in mainland Europe. Spain was a dictatorship until the late 70’s and had a failed coup attempt in the early 80’s, and was going in and out of technical bankruptcy. Germany was rebuilding after unification and was in a bit of a political turmoil with demands from the East Germans. Italy had seen a succession of minority governments for decades. France was just the safest bet they could take.