Especially important if you want orchestral instruments that sound realistic. Just think of the many ways that a single note can be played by a professional player and multiply that by the range of the instrument.

Edited to add: not orchestral instruments, and also not samples, but this gives an idea of the complexities of capturing the characteristics of an amplifier so that it can be modeled faithfully: https://neuraldsp.com/quad-cortex-updates/introducing-tina (I'm not related and I'm actually a Line6 customer, but I saw this at work in an interview by Rick Beato and though it was super interesting)