As I read it, I am with Andrea at this point.
It's a private party of friends and collegues with a clear purpose of having a partynight with active participation from all the guests including all kind of requests. There's no need for having total control over "audience" other then make sure they don't drink too much, which is not the task of the musicians anyway.
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As far as the original subject;

There is a clear geographical difference in acceptance of the arrangers.

"The more south you go the better is the acceptance"

This is the same in europe as in usa apparantly.
I am pretty often in countries around mediteranean and I can assure you the arrangers are very well accepted there.

Is this because the north european public are more seriously? Or are they just TOO conservative and not open minded for new techniques?

If I was public, music should be for entertainment which could be serious, joy, love, have fun, you name it , music has it all! I would not care how it was done as long as the music pleases me.

The only reason I am interested is the fact that I am a musician/composer myselve.

Now I am not saying that you should not take your job (if it is your living) serious!
You better do!
But if it is your profession, hence you are in the entertainment bussiness!
So your first job is to entertain!

And if you make a good living out of it, you are a professional doing fine!
But which manner you use to do it, to my opinion is less of importance!

So arrangers have their place absolutely, but how they are used? John Doe does not care at all!

Didn't we have this discussion before?