And what specific legal protections would you be caring out most that would not be addressable with a shared exit pool? Common stock options are highly limited in their legal recourse and common share owners are often (legally) shafted through dilution, restrictions on share sales, and inability to access direct control.

Anything that is worth caring about from a legal perspective can be addressed through means of a guaranteed profit and exit share versus the less tangible and more easily screwed around with common shares, in which employee and founder interests are in many ways not aligned.