I'm always disappointed in this style of visa. These are the kinds of people we want to keep, not make their stay contingent on working at or running a startup. To me, it's really stupid that anything but a tourist/business visit visa should be non-immigrant; all long-term stay visas should provide an easy path to permanent residence (sure, assuming whatever reasonable qualifications are met).
And I wonder if these W-* visas will be similar to the H-* visas, where if you quit or are fired, you need to find similarly-qualifying employment in a disgustingly short amount of time, or you're forced to leave the country. So you end up having very little employment mobility, and many people end up feeling trapped in a job they hate, because finding a new employer that will sponsor your visa isn't always a slam dunk, and plenty of things can happen to screw it up.
All this is just band-aids on the current crap immigration system we have. But no one has the political courage (or capital?) to completely throw out the current system and write a new, sane, humane one from scratch.