I guess it depends. Like Bit said, it's one thing to use them to ****e things up, but, if arps and loops become the centerpiece of your music, then, yes I'd consider it cheating.
I remember a few years ago demonstrating just that to a friend of mine who was into industrial/ebm music. I loaded an instance of Z3T4 and used the initial arp patch - the whole chord progression was in there - all I had to do was to push one key w/ one finger. I then quickly added a kick pattern. "That's how you write one of those songs".
Even funnier is the fact that a few months later, one of his favorite bands came out w/ a album and released that same thing as a song - just not in the same key.