Which would you rather: co-operate voluntarily with ATC in Class G, or get Class D imposed on you so you have to do what you're told?
Read what I said: "In practice I can't see myself refusing a reasonable request that's likely to improve my safety and that of someone else. But I think it's reasonable to expect it to be phrased as a request rather than an order."
If compliance is voluntary, I would expect the language used to reflect this. Not least because a pilot is more likely to decline to do something silly, if requested rather than ordered.
VFR flying is generally lower than IFR flight. Terrain and cloud avoidance takes up more of our attention. A VFR pilot should be constantly thinking about forced landing areas, the glide-clear rule and where the Red-Arrows happen to be flying today. Navigating a legal and safe path through UK airspace can be a real challenge, without changes to your flight plan being made at the whim of a controller.
If I were an ATC I would be wary about telling VFR pilots in class G what to do.