That is an interesting question. I cannot come up with an answer that correlates with good sense in today's world. I am accepting at face value the author’s claims which describe the aircraft involved and their capabilities, and that they went where the author said they went. We can know of course that someone in the military hierarchy of the U.S, which goes all the way to the Presidency,  made the decision to carry out those provocative missions, so that is where to look for motive.  I too rarely feel that I actually understand what the real underlying motive is or what benefit is hoped for.

One reason given in this instance is that it is for training including working with allied countries in effectively coordinating mutual effective support for an attack on the Russian mainland. Another purpose that I know was in play in the past and I assume is still operative is to gather intelligence about Russian response capabilities. When the potentially country killing air group is sent close to the Russian border all available monitoring systems are tuned in to see how quickly the Russians respond, where they respond from, and what the channels of communication are within the Russian response units involved to the extent that we can determine.  

  I suspect that a strong influencing factor is human nature which pushes people to form pecking orders of dominance in social and economic systems which too often reward bullies and usually pushes a bully to the top. Then they are called leaders. A bully who cannot win on merit alone just cannot keep from waving his stick at whoever he can get away with attempting to intimidate and dominate. The demonstration of power is like the school bully catching someone in front of a crowd and sticking his finger in their chest and saying loudly; What are you going to do about it punk? The bully always has some fans urging him on but there are usually more who wait for the grim satisfaction of seeing a David come along and kick the juice out of him.