From what I understand, the 94-95 had this as a anti-submarine feature, so if you are in accident you don't slide down under your seat belt (your knees would hit the bolster). I guess MB received many complaints about not enough leg room so they changed it in 1996.
I believe that is the only reason. Not sure if the new one can be retrofitted though. My local MB dealer is pretty good about letting me return parts, maybe you have access to a similar dealer that would let you order the part and try it, then if it does not fit you could return it. I have done this many times.