The only good enemies WW has are straight out of Roman mythology-- and this story killed them all off.
Every good Wonder Woman story either involves another major DC hero or brings in Greek and Roman mythology. Ares, Circe, Hades, and Medusa are badass villains-- killing one off and explaining the others away was Quest for Peace stupid.
The family watched this again last night, on demand.
The reason you're wrong about this – which is not to say that you don't have a point, but the reason this needn't be a problem – is because the only "source" that told us the other gods were all killed off, is WW's mom. And she has already lied to WW about Zeus' involvement in WW's origin. She lied to protect Diana from Ares. Who's to say she didn't lie about ALL of it, to protect Diana from not just Ares but all the other gods too?
The next writer can bring in the whole gang, and there's no real inconsistency.
Movie's still damn watchable by the way, even on the nth viewing, however many times I've seen it. She's charming as hell. So many little moments are super cute. The whole banter on the boat about where Chris Pine is going to sleep; marching thru the streets of London and suddenly she sees a baby for the first time; trying the ice cream cone in the train station; Scottish dude offers to quit their little band and she's all "No Charlie, who will sing for us?" Friggin adorable.
I hear the Justice League movie is terrible.