> I'm surrounded by music people and their instrument is basically an extension of themselves, they spent hours everyday touching it, for their whole life since 4. For some it's also the most expensive thing they own.

Meh. I was very into music growing up, and still play. It doesn't bother me in the least to see a musical instrument that is not my own being destroyed, any more than I have a reaction to seeing a car being destroyed in a movie ("some people really love cars!") or someone blowing up a building ("some people really love architecture!") or an artwork being burned/modified/mutilated ("some people really love art!"), or food being wasted/destroyed ("some people really love cooking!") all of which are more-or-less common in mass media.

(To wit: someone else here pointed out the OK Go music videos where they -- professional musicians! -- destroy all sorts of things, including musical instruments. Those were great, btw.)

While I do not exclude the possibility that some people may have feelings in reaction to seeing a generic musical instrument being destroyed, you can extend this metaphor to any number of areas where it's completely accepted to see similar acts of destruction.

> Some violinists are put off by music videos with violins played in the rain. Apple's ad would be traumatic.

More likely is that a few people are truly bothered, but lots of people engage in performative outrage for attention, which is so common that we have a name for it: pearl-clutching.