Why was the organization, "Jehovah Witnesses", not known by this name at their inception?
The answer to that would be due to "New Light"
The bible says God never changes, Jesus is the same yesterday today and tomorrow, but god tends to jerk the Governing Body around a bit.
Hi 4Him, and welcome to the board.
As kate said, any change in witness doctrine is always put down to God revealing a little bit more to them, "new light" is what they call it.
Because JF Rutherford wanted to get rid of everything tied to Russel.
An altertate answer would be that they couldnt very well call themselves the INBS anymore because the INBS left the watchtower group.
Russell said his followers were not to be known by any name other than Christians.
Zion’s Watch Tower 1883 March p.6
“We always refuse to be called by any other name than that of our Head --Christians--continually claiming that their can be no division among those continually led by his Spirit and example as made known through his Word.”
Rutherford took the shell of Russells failed religion, (failed in that not of his date predictions came true so the religion was collapsing), and built a new and different religion, that he also applied a new name to.
Russells relgion was about Jesus, Rutherfords was about Jehovah.