Under Russell I think it was an attempt to be sincere. Russel was a voice for those disgruntled with organized religion and started to build a following.
Under Rutherford it turned into a cult. He saw people desperate for a leader and stepped in. Not for enlightenment, but for his own personal benefit. He had new cars, lavish trips, several homes and a life of luxury all at the expense of his followers.
After Rutherford died, the WTS went into one of the largest growth periods. Here was an organization that had cult like control tactics and recruiting procedures, but no cult leader. Very appealing and deceptive.
Previously restrictive rules on their preaching work could be easily challenged now as they started to form a more mainstream religious structure. They won many court decisions for freedom of speech which earned them favorable press. The growth was phenomenal which only helped their message of being God's chosen spokespeople and it was easy for the people at the top to feel they were doing God's work.
The massive growth though, didn't come without cost. While at one time focused on publishing books for their dedicated membership, they found it necessary to start assuming additional roles. Managing the congregations, new halls, land management, policy and politics. This created a ballooning overhead to support the structure. People without any experience in these tasks were thrust into positions of controversial power over the fate of faceless members. The first priority was to ensure the structure stayed in place. For without order, surely there would be chaos. Rights of the individual may need to be sacrificed for the rights of the many.
What it meant to be a true follower of Jehovah was being changed from a guideline to law. The membership could not be trusted with making the proper decisions. Ignoring the obvious parallels between this course of action and the pharisees of old, they plowed forward. In the 70's the Governing Body was given total control at the bequest of Ray Franz and that in my opinion was the beginning of the end.
Previously, the GB only served as a sounding board to the president. They could offer their opinions and debate, but the whole direction of the movement was still led, for better or worse, by an individual. With the change of this, the head was lopped off the beast and there now lacked any true leader to act as a guide. They still had momentum, but momentum without direction isn't the same as progress.
All organizations were in for a major surprise in the 80's when people started to learn en masse that organizations could be held legally responsible for their actions. The Watchtower realizing how exposed they were started drafting up numerous changes to their business model. Surely if Satan was going to attack God's organization, bleeding them dry from frivolous lawsuits would be key. They worked closely with legal departments on mounting a solid defense while their spiritual offering suffered. The question "Is this what Jehovah would want?" was quickly replaced with "Would this make us legally liable?"
Again, focusing inward and ignoring the flock let countless members fall to the wayside from a poor blood policy, child abuse, education, corrupt elder bodies and foreign policy. But the numbers were few compared to the annual growth so it wasn't a priority.
Into the 90's came the information age. This created a global community allowing anyone to easily talk to anyone else in the world. People started to talk and share. The previous apostate efforts that lacked finance and visibility were now offered a main stage for little to no cost. People started to share their stories and the long string that the GB had wound up and hid, now started to unravel in plain sight to everyone.
Today the momentum has flipped. All those people cast aside by the callous decisions are banding together and each one chipping away at the integrity of all they have built. Still they are focused on preserving themselves. Long ago they have lost sight of why they started, God's word is now secondary to survival.
Their actions since the late 70's have all been reactionary to change. They still lack direction and if they elect a president again to break deadlocked votes, and make decisions that are good for their members, not just the organization, then they stand a chance of survival.
Otherwise, they are in a slow downward spiral that is picking up it's own momentum. Already the overhead is starting to crush the weakened organization, only time will tell if they will recover.
