I agree one should train to brake without lifting the rear wheel off the ground, but does that mean you should stop there? Why not push it even more and see what happens next?
Learning what your bike will do next is very valuable as well. The MSF is great, but their course focuses on basics... they don't claim that you'll know your bike inside out after their course... Nate's exercise will help you with that. Talk to your MSF instructor and ask them if practicing stoppies is a no no... I am sure they'll say it can only help
FWIW, I pulled a stoppie before my last accident and it most likely saved my life (per the witnesses and cops), as it allowed me to fly over the bike and car, instead of being slammed into the bike/car... I know it doesn't mean much and it cannot be generalized of course, but imo, telling someone they shouldn't practice stoppies because they wouldn't pass the MSF makes no sense.
And for the record, I did not pull the stoppie on purpose, it just happened in that fraction of a second before the accident, and I am glad it did! :thumbup: