I mean, they’re establishing a universe this Superman exists in where superheroes are already commonplace (like 93% of all DC stories). Hard to do that without showing a few of those other heroes. It’s not the same as what the last iteration did - it’s not advertisements for the next projects (we don’t even know where Metamorpho, Hawkgirl and Mr. Terrific would even appear next), it’s literally establishing a setting. This isn’t the Justice League we’re setting up here. It’s Clark’s other work colleagues he has to deal with on the regular, and that’s why they are there. They are a big part of his dual life. They’re here to serve this movie, as it has a very different type of setting than any world a previous Supes film has been set in, and it’s one that more closely represents the comics universe. Reducing them to fan-service cameos or just cheap Easter Eggs would be exactly the type of thing to avoid here, imo.