Users are not noticing the difference between 5ms lookups and 20ms lookups. They are noticing outages, data loss, and inconsistency.
I am not proposing writing any additional cross-region consistentcy code, many CRUD applications have added zero cross-region consistentcy code and just left this entirely on Postgres to handle since bi-directional replicas are now a core feature.
The more complicated you make your stack the more likely you will end up with outages, data loss and inconsistency. Using plain jane battle hardened, well developed tools that can serve the internet at scale from a single modern server gives you a very simple architecture where most of that architecture is getting significant improvements every quarter as the libre software community improves Linux, Nginx, Postgres, etc versus whatever random person Amazon is letting work on RDS or DynamoDB for the next year until they PIP them (as they almost always do).