"Your pinky is just another finger, no stronger or weaker than any other. You should be able to play using all four fingers without hesitation."
Turns out its wishful thinking. Your pinky is weak.... WEAK I tell you! Look at it, hiding out there at the end of you hand... its a wanna-be finger, the black-sheep of the finger family... the runt of the litter....
Seriously now though. Some very hard-working dexterous pro players can utilize their pinky so well it puts our hard working real fingers to shame. However, most players, be it lead, acoustic, folk, whatever will use their pinky only when the need arises. For chords, its often a necessity. You just have to practice the chord so well that it becomes a reflex. Your gets into position with the rest of your fingers without any extra effort. But for bends, hammer-ons, stuff like that, you'll see more often than not, even good players favor using their index, middle and ring fingers. Eric Clapton is a good example of a well known "three-finger player".
So moral of the story is demand and supply. If you need to use your pinky to get the sound you're after, do so and don't be surprised if its a bit of a chore at first. Otherwise, feel free to "cheat" and make it easy on yourself by using the fingers most comfortable; you'll play better, and sound better, and enjoy playing more.