The question society then need to come to terms with is to what extent it is prepared to grant that exclusionary control.
It is not clear to me how you can have a just society without curtailing property rights. Every country on the planet add substantial restrictions to what you can do with "your" property already in order to reduce the negative impact that property rights has on the rest of society, so the question is really to what extent property rights are balanced to maximize benefit.
Not to mention if domains were more expensive we'd have more link-rot, which is already really nasty.
If a website-needing company pays based on how badly it would hurt them to lose that site, it would destroy their margins. If they pay a more reasonable amount, or if they're just a smaller company, they're vulnerable to competitors kicking them offline at a whim.
Land is pretty much the only area where taxing a significant percentage of value makes sense, and even then it's frustrating and awful to do it with a buyout system.
I think in general the business should be bundled with the domain, although I think that probably there should be some oversight preventing completely unrelated domains from being bundled together.