The new light doctrine is indeed very devious and irritating also because it implies that God who according to the JWs directs their FDS is not capable of passing on to them the real truth from the first time and has to make adjustments later. This is a major foul since God simply isn't that incompetent neither does he play around with His followers by giving them misleading information.
Of course the dubs will say "but He is adding new light to the old" which of course is not the case because they do not add, they demolish and rebuild concepts that are often the exact opposite of the former ones.