I'm far from a super fan, tho I like Carol in the comics well enough most of the time other than Civil War 2, but setting this in the 90s is such a clever move, my interest in the film shot way up:
Allows them to set up Carol's backstory in a way that lets her show up in Avengers 4 already in full control of her powers, with substantial experience fighting cosmic/alien threats, as an expert. We already have Spider-Man to be a newbie, definitely didn't need two. My guess is that she'll end up being caught in a time dilation situation and take decades of our time to return to Earth in only a few years time from her perspective. Or maybe she just ages slowly and her second solo film will be a flashback as well.
This allows them to set up Skrulls and the Skrull/Kree war as something that happened in the past, setting up motivations for the Skrull to play the long game required for Secret Invasion/Dark Reign to be the next multi-phase story arc, and it also allows them to bring back Ronan the Accuser for a great cameo.
Skrulls are a great reason for Fury to be so damn secretive as to fake his own death.
Alongside Ant-Man, it gives further evidence of pre-Iron Man super heroes being a thing operating in the shadows for decades, setting the scene for Marvel to introduce characters like Blue Marvel etc further on, leading to an Ultimates movie... which won't happen unless the Black Panther and Captain Marvel films are huge hits but I can dream, right?
