In my opinion it falls under the same category as encouraging 'flat' approaches because it's 'too hard' to land off a steeper approach. If you're going to allow the required handling skills to degrade to the point where that's an issue, then something's going very wrong.
Totally agree. I could/should perhaps have worded my initial comment a bit differently, but what I am driving at is that IMHO you should
a) be able to control your a/c in all configurations
b) use the above skill to adjust to the circumstances
The a) above obviously includes 40deg flap landings!
Re the sideslipping prohibition - some Cessnas are placarded as such.