Like others have said, because everyone is using the same samples and we are obsessed with no bleed and over compressed and filtered sounds. I fought it for year but due to an unfinished basement and wee lil' kids, I converted my Tama kit to hybrid with triggers and lemon cymbals and pump it through EZ drummer or SD3. It's awesome to play on for sound and feel BUT it does sound like everyone else. So much that if I ever use it for any type of produced music, I would probably layer the snare and cymbals with my own cymbals. What is lacking in the market today (and which would likely not sell much) is a huge library of raw unprocessed and imperfect samples for drums. This would include room mics. If they want to deal with the phase issues that is a bonus but if you start with a raw sample and are in charge of shaping it as you want (or shaping it LESS), we'd breathe more life back into things again.
SD3 oe EZD need a sample pack called "Raw Rock" or "Raw Metal" etc etc...
You can open the mixer in SD3 and remove everything from the drums, giving you just the raw drum sounds. I've had to do it a few times when I couldn't get their EQ to do what I wanted. That said, I'm blown away by how well that onboard mixer works. The only thing I end up doing to the drums after I write the MIDI is a couple parallel compression busses and two additional reverb busses; I'll do one parallel comp of just kick and snare, another parallel comp with the whole kit, a room reverb and then a separate reverb for just the snare.
But until people start learning how to dial those velocities in, it's still going to sound like a robot, just a robot playing unprocessed drums.