I don't consider it a crutch, as long as you don't use it to subsitute for barre chords (the intro to under the bridge is a good example where you could do that.) Most people I know, including myself, use them while they're playing and singing (or someone is singing with them), because there vocal range is higher then how you play without a capo allows. Kind of like how some songs are tuned down because some vocalists have a lower range.