I believe the intent of sportsman was for new racers, people on a budget, and people with cars that aren't competitive in pro, like an older 800. The rule makes it easier for people to compete at KOH in almost any utv. It is literally a stepping stone class designed to boost entries.
Sportsman cars are very unlikely be driving over each other. Not that we do it in pro, but that's part of the roof requirement. It's also for big rollovers on huge obstacles, which are less likely in sportsman since they cut out most of the waterfalls last year.
It's an entry level class. If you've got a fast car and you're comfortable driving it fast, step up and run pro.
I'm sure that if people start showing up and pushing 90 mph in sportsman, Dave will take another look for 2016.