You're making too many presumptions. Including Lois Lane isn't about connecting Wonder Woman to Superman. Apparently you don't recognize her as her own character in the DCU. Making up another Pulitzer Prize journalist just to serve the same exact purpose as Lois is tedious and redundant. That's what would be unnecessary. Not to mention that Lois has the most experience covering metahumans, so it's completely realistic that she would do it with her high profile. It's how the real world works. Sure, it doesn't have to be Lois Lane, but it could be, there's no good reason why it shouldn't be her, and that's how it was in the comics.
There are plenty of characters that aren't essential to a character's origin that are included in an origin movie. Was Colonel Hardy essential to Superman's origin? Hamilton? Faora? Zod? They could have used different villians instead. Was Bruce Wayne's satellite essential? The story dictates what's necessary and essential. And, not every detail has to be about necessity because movies are works of art, not a machine.
If you think WW's origin alone can fill up 2 hours and tell a meaningful arc, I don't know what to tell you. Origins are meaningless if you don't show events that establish the character's importance. Look at every superhero origin movie. It's not only about their origin. There's always a plot that pulls the protagonist towards a challenge to overcome. The character has to do something after they get their costume.
These characters are key players in the DCU. It would be less believable if they didn't interact. You can be against it all you want, but that's not how films or comics work. Events and characters are suppose to be interconnected in a shared universe. Making WW's origin very contained doesn't make much sense. Like I said, it's part of her origin story for the outside to enter her world and for WW to join the rest of the world. It wouldn't be smart business-wise either. WW is sandwiched between BvS and JL. Why would they have the WW movie ignore that when they could use it to draw in more people into her movie?