Current thinking (at least what was put to me in my FIC last year) is the CAA don't want us to teach wing down.
Apparently even if the plane is easier to handle on final approach it is still safer to crab thus reducing the risk of Spinning on approach.
Mind you all it takes is a change in the commitee at the CAA and the policy will be reversed. I was also told that i would fail my CPL and IR if i did a wing low approach during the flight test.
If any examiners out there can confirm or refute this I will be happy to stand corrected
MJ