It is of course completely illogical. However, given the mental numbness displayed by the rank & file, probably very few even noticed (and probably only near-apostates actually acknowledged or questioned) the change in "generation". The rest probably praised it as new food from Jehovah.
This all stems from fundamental doctrinal falsehoods - one, the literal 144,000 being the only ones to go to heaven; two, the idea that the Christ's rule began in 1914 and that the generation thereof would see the ultimate end.
Just the fact that the remnant of the 144,000 still partaking of the emblems refuses to go down in number shows the insanity of holding on to these idiotic ideas. Not to mention the fact that practically no one actually alive in 1914 and "able to discern the Watchtower ideas about it" is still alive. After all, the news media is now reporting that only ONE WW1 veteran still lives here in the U.S., and that the last survivor of the Titanic shipwreck died last summer in England - and she was a tiny baby on the "night to remember".