Because owning the patent protects you from predatory companies. Any technology you use that conceivably could be patented, but isn't yet, is a legal risk - and "conceivably" includes things that are obvious, absurd patents from a developer's point of view but that the Patent Office might approve anyway.
It doesn't matter whether or not you plan to do predatory lawsuits. The current nature of patent law means that the incentive is to get away with as much as you can, as soon as you can - or else somebody else will get away with it and earn a chance to sue YOU.
Moreover, if you want to get that prior art on record with the USPTO, one way to do it is to file for a patent then let the application lapse before issuance. It'll then show up on subsequent searches.
We used to do that as a standard procedure.
Before a meeting with a client we would write a bogus patent listing everything we could think of about the subject. Then if there was an arguement about an NDA we could prove we were already working on the idea.
You can file a PCT application for almost nothing (used to be $20) and never bother taking it to a full patent - cheaper than having a lawyer minute it.
The risk isn't that somebody else could patent the technology. The risk is that somebody else already has a patent that could be applied to your technology. If you can get a patent for your technology, that makes it much harder for somebody to stretch their patent to cover your technology, because the presumption of competence on the part of the USPTO leads to the conclusion that the two patents cover different things.
> It doesn't matter whether or not you plan to do predatory lawsuits.
So because Patent Law encourages Microsoft to get away with as much as they can, as soon as they can, they are not longer 'at fault' for predatory lawsuits? We can absolve them of their crimes then? That somehow seems wrong.
The 'War on Drugs' might encourage drug dealers to be ruthless in an attempt to evade the law, but I'm certainly not going to forgive them for any crimes that they commit as a result of trying to evade the law just because 'the system encourages it.'
It doesn't matter whether or not you plan to do predatory lawsuits. The current nature of patent law means that the incentive is to get away with as much as you can, as soon as you can - or else somebody else will get away with it and earn a chance to sue YOU.