Why would you not want any ramp down with drum samples? I suppose most of the time those are one-shot samples where you wouldn't apply any volume changes anyway.

Look at it this way:

When most notes begin, we can usually be assured there won't be any pops in the sound. As long as where the sample begins is at flatline level, we know it won't pop.

Sample end however, is ambiguous. We don't know where the sample gets cut in a note cut. That being said, Ramp-Down is an important parameter and I'd place it explicitly on the instrument.

Some instruments I might want to give more Ramp-Down than others. Sines waves are a perfect example--I pretty much always give them more Ramp-Down. Pops will clearly be heard when a new note 'cuts out' the older one unless a good amount of Ramp-Down is added.

But as I said earlier, there are often times when I don't need volume Ramp-Down at all. A good example are saw waves. You can't hear those 'pop' because of their brightness. I've also noticed the Ramping can add unwanted artifacts to the sound, so most of the time I try to avoid using it--only use it when I need to.

Besides, every time I need to change Ramp-Down, I have to access the setup. I'd much rather save the Ramp-Down to the Instruments where I need them.