Can't agree more to this post.
I love these movies, and as a kid I laughed so much. The style of Kung Fu, the epic fights and movements. Stunning.

“Everybody is Kung Fu fighting!”

Stephen Chow, and the Crew, are great. In the sense of acting, comical and the potion of message.

I like your point of view.

"...during the fight Sing intervened and saved the couple, and this was the plot flaw.

How could Sing go against the gang he has always wanted to join just a day or so after being accepted? After it was his life's goal to join the gang and he had done a lot of stuff for years trying to join?

But isn't that the message? Fighting for the weak and good. One of the philosophies of Kung Fu.
Fight against those who abuse their power, place themselves above others and take advantage of them.