I believe the possibility that a developer capable of understanding and creating this local MITM not being aware of the wider security implications is near zero. That would be like a scientist understanding nuclear fission and bomb making not knowing that detonating it in the middle of a city would cause a lot of deaths...
The MITM framework was created by a separate company from the company that developed the specific piece of software. Just like you don't actually have to have a clue how a web server works to write a Rails app, the Superfish developers bought an off-the-shelf MITM framework and used it, which doesn't require much thought.
