It's unfortunate to hear that you are so personally offended. I assure you that the people who implemented this policy were probably not aware of your existence when they made it, so I hope that knowledge helps to lessen the amount you feel personally insulted.
The sad reality is that this policy works extremely well. 50 reputation points is not difficult to come by for any users that intend to contribute more than one or two opinions. It is not restricting commenting to the elite users since any user that spends a day or three on this site could easily accumulate the necessary reputation if they wanted to.
Although you seem very avid to have this policy changed to something more to your own personal liking, you need to realize that there are a significant number of other people that use this network; majority of whom enjoy this policy. That means that in order you to change this policy to what you want it to be, the owners of the site would have to change it away from what the vast majority wants it to be.
You asked in your post that we be fair to everyone here and you imply that the reputation requirement be fair, logical, and achievable in a reasonable amount of time. That is a noble request. It's understandably impossible to be fair towards everyone all of the time, but we can strive for fairness to the majority. The current policy satisfies the wants of the majority; it is in place to decrease the occurrence of spam, trolling, etc; the necessary rep is low enough that it can be earned by writing one or two good posts or through 25 approved edits; and it is widely agreed that it works well and does not exclude anyone unnecessarily. These make it fulfill the requirements of your request. In trying to be logical, reasonable, and fair towards the greatest number of people, it is a good idea for us to leave the policy as is.
Unfortunately, you may still view this as unfair or unacceptable. If so, the only thing I can tell you is that some things in life will seem unfair to you and some things can not be made to change simply because you disapprove. Learning to live with and not be angered by minor inconveniences (and that is exactly what this is; not being able to post a comment on Physics.SE is no more than a minor inconvenience in your life) is something we all must do. Life sometimes isn't fair.