Like Laan it could have been a new character doing this. Uhura was not needed as with Kirk or Sam. if uhura is the young one as you say,  then why are chapel spock and kirk not the young ones? why her and i am sorry the most iconic of the females from tos.
Zero inconsistency. Kelvin trek at least got this right. like TOS it cast all the actors  around the same age. Uhura been significantly much younger than the rest of the group or the young one should not have been the case and I do think changes a lot of the dynamic.
SNW wanted their young innocence character POV like most star trek does with Sato Crusher and adira. but they should not have used an established character like  uhura for that. Just create a new character same with khan-laan.
chapel I would even pick to be  the young one because in the original show she could be shy,  lacked confidence and sometimes felt out of place away from the core 7.
 Also when you take into account in tos uhura always came off more confident with a bigger personality. It may have made more sense to make chapel the young one and may be easier to explain her crush on spock in tos. a young girl who had this crush on a older guy that did not return her feelings. they could have played the spock/chapel thing  like that than the mess we got in snw that we know does not fit tos timeline.
can you imagine rebooting Friends and making rachel green a much significantly younger character than the rest of the group chandler, joey and the rest? this to me is the equivalent of how they handled uhura on the show. while I do not think this is like the worst thing ever but it could have been better. as with quinto spock, saldana uhura was much closer to tos uhura.