This is exactly right. No defensive patents would solve a lot of problems in this system. Patents were supposed to be about protecting innovations coming to market...
Hold on... You've got a *very* basic misconception that's probably influencing your thinking on the topic of patents. Patents are *supposed* to be about ensuring that the knowledge to create an invention are shared with the public, rather than being kept secret and being lost to time as a result.
The method used to encourage this is to provide a temporary legal monopoly over the practice of the invention. (That's not a goal, it's a method.)
How exactly would you get rid of 'defensive' patents without also getting rid of 'normal' patents?
My own solution to the patent mess involves putting the protections and incentives back with the inventors as follows:
1) Patents belong to the inventor or inventors (actual people) listed on the patent. (Normal laws which make it illegal to incorrectly list or not list people still apply.)
2) Patents can be licensed freely, just as they are now.
3) Patent ownership can *NOT* be sold or otherwise transferred. (Period. Full stop.)
4) Add a method to challenge a patent's validity in so far as the required description of the patent. (If an appropriately skilled team cannot implement the invention *solely* by reading the patent, then it does not fulfill the basic requirement that it must accurately and completely describe the invention, and it is invalid.)
Suddenly, the industry would be fighting to keep patent terms (length) reasonable, and ensure that patent filings actually contain the requisite information. And, the number of patent applications might actually drop to only include things that are actually *worth* patenting.
Similar changes (1-3) to copyright law would might get it pointed back toward the direction of sanity again as well.