Many Postgres features and packages can be enabled / disabled via configure, and the engine built, if you want a "leaner" deploy.
All RDBMS engines have a variety of features that are not necessary in all deployments.
All RDBMS engines have a variety of features that are not necessary in all deployments.
While it may seem nice and convenient to have all these different features in one nice package, I'm struggling to see what that's such a good idea in the long run.
The thing with the separation of concerns means you use software that does one thing and does it well. Maybe this comes with a greater maintenance cost, I don't know, but I think I'd feel safer with that, because of the maintenance reasons you list.