Quote Originally Posted by Katsushiro View Post
I didn't even pay attention to that because EVERY other moogle tome prize event has let you spend them afterwards... WHY is this one different?
This one was different because it was done specifically for the FF2021 Fanfest and added three things that are not normally a part of the mog rewards. Those three things SE likely does not want to have available through other means and may never be added to the moogle rewards again. As it states in the announcement on the lodestone. Now the absolute reasoning as to the why is speculation but based on the information given it is the most likely. True they could have had a period of time after the event ended to turn in the tomes for reward still, but that doesn't chance the fact that they were open and blatant about this moogle treasure trove being different from all the ones that came before it.