Actually, this has more to do with the fact spastic (or the more common slang abbreviation, spaz) doesn't carry with it much controversy in the United States. Apparently, it's not used in the US as a derogatory pejorative for people who suffer from cerebral palsy like it is in say, the UK.
http://en.wikipedia.org/wiki/Spastic..._United_States
So it's more to do with Hasbro being an American toy company (and not being aware that term is offensive in some regions), essentially a cultural misunderstanding, than any lack of regard for the Transformers franchise.