I'm all for foregoing a connected universe (that isn't that connected anyway, yeah I'm looking at you MCU), and make good movies. If they happen to have other characters involved, great. If they mention other events or events in another movie caused something to happen in another, great. If there's no connection at all, great.
It's like the DC animated stuff. Sometimes they reference preceding movie events and that's it. Sometimes they have characters X, Y, Z but not all the time. This way directors and script writers can do a lot more while still being able to reference things that came before or is still to come. They also don't have to setup a team up movie with 5 others before it. They can just do it. There was no setup for Flashpoint Protocol. There was no setup for Justice League War.
That Batman/Batwoman animated movie has Damien from the several previous movies and at the end, they show
who will presumably get a movie in the future (or not).
That's the way to go. Connected, but not connected. Free to drop characters in and out but not restricted to a set of rules. Mention past events or tease future ones but they don't necessarily have to go there.