In the (philosophical) literature on property (what can be owned) there are two main principles what constitutes property, these are scarcity and effort (labor).

For instance jackets are scarce, not just because there are a limited amount of jackets in the world, but because if I take away your jacket, you do not have your jacket anymore. Or if woods are scarce we can make sure that woods will not be exhausted/exploited by making it the property of someone (hoping (s)he will be a good caretaker). Anyway it seems to me that's not the case with intangible property (especially if it's in digital form). My reason for this is if I take away (a copy) of your code, you still have your code. So I think the exact cost of making a copy is irrelevant here.

On the other hand, the principle of effort stands still for intangible property. If you mix your labor with an object (in the lockean sense) that makes the product yours. The product of your work would not exist without your labor. But this reasoning stands for the first copy only, the effort after that is the effort of copying.

So far so good, but... there are a lot of "but"s. Just to mention some:

If digital goods are not scarce (in the technical sense), the legal system of a society still can make it scarce, even with a good reason. That's reflected in most of our legal systems by the fact that intellectual property is a limited right (in time). So to say intellectual property is legitimated by making the creation of IP a profitable business (to encourage the creator by giving this limited right to her/him). However I think it's a sad joke that we're calling life+70 years limited.

Another major point is the (legal) security of property. If someone owns something right now, we should not transform this to something not ownable, because it hurts the interest of many.

Another one is that there were a lot of things considered IP before the time of digital machines and the internet, however at that time the ordinary folks were not able to copy and distribute them en masse.

In the end I think the nature of digital goods is not represented well in most of our legal systems. However I do not expect any serious change in it soon, because the property right is so deeply permeating any of our society that it can change only on the scale of decades or even centuries.

I hope this was not too abstract to make it irrelevant in this thread.