I'm kinda with MiRai on this one (although I'll allow LED's as long as I can dim them to an acceptable level/disable them).

I have a mouse (a G300s currently), which has 9 buttons if you believe the marketing blurbs. I use 3 of them. Left click/Right click. The 3rd one is the DPI change button, for when I've somehow changed it and need to change it back again. Oh, and the wheel up/down.

For the other hand, I have a G13 for gaming which gives me access to multiple keys very easily, along with various modifiers, or even a complete keyboard output shift, if desired.

I also use a G910+ for normal stuff, which has 6 macro keys, which I do have setup for various functions, but they mainly get used for testing configuration items before I push them out.