Keith Richards recently gave an interview to Marc Maron on his podcast that's definitely worth a listen. There's a great section forty minutes in where Keith shares his opinions on using guitar pedals:
"Hey man, it's enough to stand up straight, let alone poking around on buttons, you know. And also, any of those effects that I need can actually be done from behind. If we need tremolo we can do it from behind. Because I need to know where to put my feet. Tripping over those boxes, it just ties you down."
Check out the full interview here.