People being afraid of liter bikes makes no sense whatsoever. Probable and old wives tail propagated by motorcycle dealers to get people to blow money switching bikes over and over.
I have seen plenty of people riding 1000cc bikes like old grandmas in a town car. No adult is automatically compelled to pin the throttle there a plenty of people who just like sitting on a powerful motorcycle and never use 1/3 of the bikes power. Just like some people like 500 hp+ cars that just like to cruise around in badass car even though they never go fast.
What gets riders in trouble is not being able to corner well. You need a bike that you are comfortable sitting on. If you are not comfortable you are not going to be confident and without confidence you are going to fail in riding. That is why the motto goes, look, lean, and believe. Believing is crucial in riding.
I supposed it's similar to an oil thread - opinions vary, but here is my thinking: I agree that comfort is important, but I think that confidence alone is not enough - you need skill matching your confidence. And humans are not exactly known for their ability to correctly identify risks and correct estimation their skills (average driver thinks that he's better than average)
A beginner is bound to make mistakes - downshifting unnecessarily, releasing clutch too rapidly, stalling the bike. MSF course cannot possibly make people go through those mistakes to learn how to recover - those skills are acquired over a prolonged period of time and it's important to have a machine that rider can handle. Modern sports-bikes are designed to provide A LOT of power and great handling to their riders - they are high-performance machines not very different from those used on a track. But all that handling and power also requires skill.
Learning to ride on a liter bike is like learning to drive in a Ferrari. Is it possible? Of course. Does this car make it more likely that the new driver will make a mistake? No. But is it more likely that the racing ponies will not forgive that mistake - absolutely. Why not take little non-turbo Subaru that handles well, won't win any competitions but will be more forgiving if you accidentally floor it (or not accidentally - maybe you are just trying to make it up that hill.... trying... trying... ok, we'll wait for a better wind)
Also, in my opinion, high-powered engine leads to over-confidence as the rider is learning to ride. I think when learning to drive, the most dangerous are not the first 30,000 miles when the driver is cautious, but the next 40,000 when they think they have experience which leads to over-confidence. Riding miles are different, the concept is the same
Additionally, learning on a less powerful bike also teaches the handling and working the clutch rather than simply relying on "power reserve" - that's why you see those "grandmas" on liter bikes left behind in curves by a guy on a "small" 600 cc.
There are plenty of riders out there riding liter bikes and not using full power available, but it takes skill to recognize the situation and unleash only the correct amount of power and I doubt that those guy learned on those liter bikes.
Anyways, just my 2 cents.