First, you say building replicator is pointless without giving an argument. This is clearly wrong. I have already given you one example of the use of creating replicators, and here's another: weapons.
Second, you say it is difficult with many failure modes. So was going to the moon. How can you possibly think it's so difficult that it will never get done? In a thousand years?
Third, you cite Drexler to claim that we underestimate the difficulty. (Who underestimates it? Me? The irrational people who Drexler is afraid will take away his funding, or the handful of academics who seriously consider the issue?) The argument for extreme caution does not rely on it being easy to build run-away replicators, only that it is reasonably possible and that the results are catastrophic. Can you really argue with 99% certainty against the feasibility of future technologies without any sort of restriction based on physical law?
Fourth, you say you are aware of the wheel argument...so...what is your reponse? Should we also consider the laser argument? The computer argument? The space-ship argument? Or the argument from any of the nearly countless things that humanity has created in the past 40 years that never existed in the previous 4,000,000,000 that life was around?
