your first point wrongfully assumes that the patent system is the dominant mechanism for spreading inventions. it may have been intended to work this way, but this is not how it works in real life.
if you have ever worked for a software company that has a competent legal department, you know that you must stay away from patents. under no circumstances are you allowed to communicate that you have looked at any given patent or even acknowledge the existence of a patent.
patents are treated with more fear than toxic waste in IPR sensitive businesses.
besides, if you don't publish and you do something clever, how long do you think it would take for the competition to figure out what you were doing? or for people in academia to publish something on it? or for some independent blogger with too much time on his or her hands?
I wish people would consider reality rather than some make-believe world that does not exist when thinking about patents. so much time, money and intellectual energy is wasted on this nonsense. not to mention that it is clogging up the courts with absolutely pointless legal battles.