One can argue that the Stingray Special was a huge upgrade and improvement. EBMM significantly modified the sonic character of the bass to make it more Fenderlike when the the player wants that sound. Most importantly, EBMM took complaints about excess weight to heart. Now, a 8.5-9.5lb Stingray is not a unicorn. Those were huge changes that were greatly appreciated by Stingray fans.
Of course, wider string spacing does not seem likely for all of the reasons we have already discussed.
I still remember when my local shop had an anniversary model about 10 or so years ago. They jokingly handed me a 5 string and it had to have been 13lbs+. My Conklin 6 string is about 12lbs and a pretty big bass. The EB body wood must have had density like concrete.
Nonetheless, the Stingray Special has some nice enhancements. I have become a sucker for roasted maple and other roasted/torrified woods when available.