Well, you'd think that would work, but there is something that I can't quite put my finger on about cymbal samples that doesn't sound right when put into the context of a song. Plus, there are tons of pre-recorded samples out there to use already, as Robert D mentioned. Still, something is missing. I think it has something to do with the nuances of the way the cymbals are hit after certain drum passages, such as rolls, fills, flams, etc. A pure sample of a pure cymbal hit doesn't capture the myriad of different ways that cymbals can be hit during the course of playing the drums. This is similar to the problem that would occur if one were to just play a standard sampled note of, say, a guitar, saxophone, or pretty much any other instrument when the note is triggered - the expression is lost.
The e-drum manufacturers have done a pretty good job capturing the expressive hits of the drums themselves with the pressure-senstitive pads that can determine the velocity of the hit and play the associated sample accordingly. But even then there is something lost in the way that a drum reacts to being hit while it is still resonating from a previous hit. This aspect doesn't seem to stand out in my hearing of a recording of a drum kit, but it does when hearing the cymbals. As I said, I don't know why it does, but I can definitely recognize it when I hear it.