I like the outside-the-box thinking.
I'd shy away from a "Class IV" river, but there's a huge difference between that and a single Class IV rapid in the middle of an otherwise II-III run, especially if it isn't holey and has a good pool below it.
I do agree it could lead to some bad habits, so it wouldn't be a bad idea to make sure an inexperienced paddler is coached by an experienced paddler to make sure that good technique is emphasized.
If it gets more people on the rivers instead of home watching TV? Good for them.
Hey, it's a free country!