One of the problems with GA aircraft is the lack of a DDG: dispatch deficiency guide. At least the airline I flew with, called it like that. You could find the equipment that was mandatory to be operational or functional. There were options like needed to be repaired immediately, fly back to home base and repair, repair within 100 hrs or so. Many possibilities.
With GA aircraft You are left to swim.on Yr own. A technician might decide different than the pilot, and all pilots will have different views because of experience and kind of use with the A/C.
Like with this horn, I still don't know if its mandatory or not. The EASA minimum equipment list does not specify this.
I flew thousands of hours on a C172 and I could live w/o it, no problem. The Cessna warns more than enough for me to know I am dangling on the last kilos of lift. It hardly wingdips, IF any. Long time ago I did banner towing also and we used to put a rag in the hole of the stall warning opening inside the cockpit. Annoyed for the hours on end of blaring. IAS was something in the 40ties.