Today, with more CPU power, memory and storage available, 40 or more different recordings can be organized to serve a single note. We now understand that every single pitch can be played with 10 or more key switches, at 5 or more dynamic levels. This makes it abundantly clear that in order to map an instrument, we may ultimately end up with thousands of samples in order to deliver the quality of coverage desired.
Of course, it is now also possible to arrange a single phrase and make it sound considerably more realistic. However, the point is that choosing the appropriate sample for each note is hugely time-consuming. It can take a vast amount of time to add bending, expression, modulation and other desirable midi controls.