I think keyboard players get a bad rap. Guitarists keep the same sound, more or less, with minor modifications. People don't have a problem with it because, I'm assuming, guitars are just supposed to sound that way.
Keyboardist are expected to change because they can load 5 billion different patches. I too think keyboardists should switch it up but if they have a great go to sound like Derek does, then I think its great, especially if it's a signature of theirs.
I've always felt this way.
Every guitar player can be identified by their unique tone but when a keyboard player has their own somehow it's not cool and I don't understand that.
I'm on the fence with this.
On one hand, yeah, it's weird that we don't demand versatility in sound from guitarists, bassists, drummers, but we do when it comes to keyboardists.
On the other hand, just listen to old-school Deep Purple. Jon Lord had such wide variety of sounds, and he was basically "just" using a Hammond organ. Case in point: "In Rock". There are no two songs on this album in which the organ sounds even remotely similar (compare the delicate softness of Speed King or Child in Time with the raw, heavy sound he had on Black Night or Hard Lovin' Man). He achieved all that variety by messing around with the drawbar/percussion settings and switching between Leslie and Marshall speakers. That's it.
These days, with the overabundance of technology and equipment, it's not unreasonable to expect more variety.