If one were to make a concise answer to what was the motive of the all the leaders of the WTS/JWS it would have to be placing the power of god in their own hands in an effort to lure and control others.
To accomplish this feat the leaders of the WTS had to spin up doctrines, lie and coerce people to themselves by the literature these men published.
Openly identifying themselves as god's chosen ones for being so honest, righteous and loyal to god's will and purpose was part of the scheme. (1919)