The Wikipedia summary of the case suggests that the ruling was much more than it was. Courts tend to rule on narrow issues, as it did here.

The question before the Court was not whether a domain name is a form of property. Both parties agreed that a domain name is a form of property; that wasn't in dispute. The Court did affirm their shared position in black letter law, though.

Rather, the question before the Court was whether, as intangible property, a tort of conversion claim relating to the domain name could be made under California law. Previously, cases disagreed as to whether it could be recognized. The Court found that it could be.