people stop with suspension due to time/money/personal reasons. while chassis flex is bad, for street applications it's not horrible. a stiffer chassis will give you more road feedback (ie you'll feel the bumps more and more) and some people don't want that. Just with my current suspension, I can always tell when I drive into the neighboring county as the roads get a lot worse
IMO, you can never have enough chassis support, and I too want to go the route that you're taking when I get the time/money