"If IP is real property, it should be taxed."
Surely it is taxed already by profit related taxation eg corporation tax in the UK and I'm sure most other countries have a similar one. Also any sales tax or VAT will capture some loot back to your friendly local Exchequer or equivalent.
OK let's get down to brass tacks: What you seem to be asking for is that if someone can be allowed exclusive rights to something then they should pay for that privilege in some way. That seems fair enough to me but you need to define what exclusivity really means and what sort of return should be sought by the authority involved. If we look a little deeper still: what on earth is IP? You also seem to advocate that if the IP is important enough then it can be purchased by the authority and that authority could release the IP to the commons or a form of commons.
You give away where you are from with the abbreviation USPTO. So we are going to need an internationally agreed definition of IP, if we are even going to begin this discussion (which has already happened and is enshrined in ... some international agreement that I can't recall).
Back in the day there was a somewhat backward colony belonging to a super power, located to the left of the Atlantic ocean. That colony grew, expanded and exploited its natural resources. That colony also had a pretty fast and loose approach to notions like copyright and patents. That colony only acknowledged their own local notion of patent and largely ignored any objections from the right hand side of the Atlantic for quite a while. OK, I'm taking the piss but not much. There's another modern equivalent to my "left pond country" these days - more than one.
So, let's start again: What exactly is IP and how does it get enforced, paid for or protected or whatever?