Nice observation. In all my years of playing those 2 chords, I never noticed that.
i was watching this Jamal Hartwell vid on youtube with him breaking down "More than Anything" (i think the link was posted either here or in the keyboard forum) and he talked about using perfect 4ths for a walk down, and then i go "wait a minute, thats nothing but an inverted suspended chord" but the sweet part is playing with other notes in the bass than what u got in that chord, which is what he did.
the cool thing is that either the sus2 or sus4 chord is a diatonic chord for EVERY degree (for some its both), except the 7. So u can play just about the whole zipcode in suspended chords and not step out of the key sig with any note, not even once. actually im gonna go play around with that when i get to rehearsal tonight.