You are, indeed, rationalizing that, because you obtained some items legally, it absolves you from obtaining others in a less than legal fashion. That is bollocks, and as near as i can tell, so is your claim that this is consistent with the aim of copyright. You can try to reframe it however you want to make yourself feel better. It's certainly not comparable to depriving someone of their actual property. But it's not on the up-and-up in any way.