People who are good storytellers already don't need writing exercises.
I think we have a fundamentally different understanding of the purpose of these exercises. I'm looking at this as having a purpose of taking people who aren't terribly comfortable with the process of creative writing and guiding them through what they really need to know for a given subject. You seem to be looking at it as just providing prompts and the user will figure it all out on their own. I feel confident saying that your method will likely not produce the results you're hoping to help people achieve. That is, actually becoming better game writers.
Yes, some people will be perfectly fine with 'write 1 paragraph of backstory', impfireball as a case in point. Those aren't actually the people I'm looking to help with this. The people I'm looking to help are the ones who routinely write "Bob hits the troll with the sword". Those people may not even be aware they could be including more, and when it comes to including more, they don't know where to start. They already know how to have Bob hit the troll with the sword, they just don't know how to say it well.
Along those lines, some people will be perfectly fine with 'stat this up'. If they aren't, this series of exercises is not properly equipped to help them do it. They need system specific help. That's why I made it optional.
I'm sure you'll disagree on every point, because you always do, and I really don't care anymore. If you still want what you want, then change the wording of the offending parts yourself.