This claim is baseless. Please reserve it for after various MOOCs have tried different models and the data supports it.
It's possible and even likely that the schedule contributes to motivation for many, but my experience has been the opposite and I'm probably not unique.
You are not unique. I much prefer studying at my own pace, too.
I found class timescales so demotivating I dropped all the Coursera courses in favour of the Udacity ones as soon as it became obvious other things in my life would keep getting in the way.
You can. But you wont.
The sad fact is that deadline motivate people. Without having deadlines and structure coursera would have gone nowhere.