Those are some good points. However, the Watchtower organization can tap dance their way around these points by highlighting the fact that they are now officially called "Christian Congregation of Jehovah's Witnesses", and that all members thereof, give a public witness regarding Jehovah God and His rulership. As surogates to the "John Class", they are assisting in delivering a "witness" or testimony regarding Jehovah's purposes for mankind. Unfortunately, rank and file JWs do not really give this area of doctrine the depth of consideration and Biblical analysis that they should. They are satisfied to repeat the Watchtower's talking points.
Rutherford's selection of the name Jehovah's Witnesses was indeed arbitrary; and based upon a self-serving desire to distinguish themselves from all other Christians. In the book of Matthew, Christ stated that his disciples would be "witnesses of me"; not witnesses of Yahweh. He also stated that "where two or three are gathered in my name, their I will be in their midst." Again, he gave no injunction to gather in the name of Yahweh; or Jehovah. To simply identify oneself as a "Christian", was more than sufficient. Even when apostasy crept into various congregations in the first century, the Apostles did not see any need to branch off and make a "name change" to those following the "true teachings". There was no evidence to suggest that any congregation changed it's identification (from Christian to Yahwah Witness) whether it be Phillipi, Galatia, Antioch, Rome, or Corinth. There was also no need for a religious organization 1,900 years later to expand on or clarify Jesus' words by making a name change.
Russell himself had initially taught that the Bible Students should simply identify themselves as Christians without attempting to form another sect or exclusive organization. But this line of thinking soon fell out of fashion, particularly after the failures of 1914, 1918, and 1925 caused many of the Bible Students to split off from the Watchtower corporation and meet independently of the leadership in Brooklyn.
The name Jehovah's Witnesses served the purpose of separating themselves from all other "false Christians", the disaffected Bible Students who repudiated the Watchtower leadership, and to bolster their exclusivistic claims. The name change had more to do with self-serving grandiosity and a cynical pragmaticism than it did with any Scriptural foundation.