Why I like this sketch: it’s ramshackle. From Graham Chapman’s (presumably booze-related) line flubbing, to Eric Idle’s building prop not working properly (watch his right hand at around the 3.30 mark), it’s the rough edges which give Python a lot of its charm for me. Plus you get a great John Cleese tantrum and I learned the word “sedentary” from this sketch. It’s edutainment.
I also like it cos it’s funny, and cos I think a lot of buildings could be improved by the addition of rotating knives.