Everything has been done before.
Dr. Dre is rightfully regarded as a genius, for example, and many would cite "The Chronic" as his career highlight. However, musically the vast majority of "The Chronic" was nothing more than slowed down samples from the P-Funk (George Clinton's two bands, Parliament-Funkadelic) movement. Dre even called the sound G-Funk and wore a Funkadelic shirt in the video for "Dre Day". He even got George himself on a track that didn't make the cut for "Doggystyle".
Does that diminish Dre's creative uniqueness? Of course not. Dre took something, and made into something else to appeal to a different market.
If Owl City was indeed inspired by The Postal Service, who let me state again, were not the inventors of ambient electronic synth pop, then he took something that was underground and indie niche, and commercialized it.
For the record, I don't consider the download of music to be "basically stealing" it.
I don't get my panties in a twist when I track the bootlegging of my own band's music (for the record, something like 400,000 unauthorized downloads of our last album from various torrent trackers, forums, etc). In Seattle I even saw CD bootlegs of our albums in an Indian store, with random ass artwork and songs from other albums tacked on. I didn't say anything about it, I didn't really care that much.
Unauthorized downloading happens. Trying to stop it is A) futile and B) just gonna prevent you from building a fanbase.
That's why I offered my own EP as a free download with the option to pay for it too. It worked. Although 90% of people download it for free, the ones that do pay for it respect the stance enough to pay good sums for it. I've had more than a few people pay $20+ for my 3-song EP.
Future monetization of music will not be through selling physical/digital copies of the music itself. That day is done. I've given guest lectures at Universities to media degree students and that's been one of the main topics of conversations. I'll be doing the same next year at DIY music conventions.