Tbh I would have liked Fates more if this were the case. My problem with Avatar characters who do have a part in the main story (Robin, Corrin, Byleth, and Alear) is that they have no personality (I know that’s kind of the point), nothing that makes me care for them or want to see their story through to the end.
If Azura was the main character we’d get someone who has a past with both families that goes deeper than what we’re told with Corrin, which would make the decision of choosing so much more interesting to watch.
Plus, you could explore the history of Mikoto and Arete’s relationship & Valla’s history through Azura if you choose Revelations. And it would give us some much needed lord class & weapon diversity.
I’d also be intrigued by if Lilith, Corrin, and Azura were all the main characters of Fates & maybe remove the choosing plotline?