What is it about now and coconut horses that I am left out of?

Plus the actors (at least some of them) had no interest in learning to ride horses.
I thought this was a perfect example of a limitation making art for the better.
Much like how the mechanical shark in Jaws kept malfunctioningso the movie became more frightening because the shark was mostly unseen (like in real life).
Having no horses meant for a stupid and funny solution : bang coconuts together.
Which spawned one of the funnier sketches in film: Where id you get those coconuts?
Which spawned a good running joke about swallows.
Having the coconuts throughout the movie was a good choice for continuity.
having it be a one-off would have been like a gag in one of Mel Brooks lesser movies.

They just didn't have the budget to use real horses

It's a running gag; a type of joke the Pythons were quite fond of. Personally, I liked it, but you always take a chance on the audience tiring of a running gag, as it appears you did.
Still, no harm done. As you said, the movie is hilarious, regardless.

• You may have come on no bicycle, but that does not say that you know everything.

no, that wouldn't have worked. knights are supposed to have horses. that's what being a knight meant.

I just watched it yesterday. I thought the no horse joke got funnier as the movie went on.
And each time you watch the movie, the joke just keeps on getting funnier and funnier until you inevitably die laughing. Not a bad way to go really.

Definitely!

YepDISMOUNT made it all the more funny !

Then there's no "DISMOUNT" joke

I just watched it yesterday. I thought the no horse joke got funnier as the movie went on. I got a laugh everytime the heroic music came on and they were pretend riding with the coconut shells.
Hows the pie?
Sooo good.

So, you would have a king just walking about the countryside like a commoner? No, that just wouldn't do. They had to keep their mounts the entire film.

No. It's always funny.
Can't stop the signal.