It's ridiculous to abandon all female-led movies because one did poorly. They wouldn't cancel all movies with male leads just because one did poorly. It's gross sexism.
Perhaps, but as a business decision it makes sense. Think about it, the audience for superhero films is overwhelmingly male. Men, in general, tend not to consume genre products with female leads and there are usually not enough female fans to pick up the slack.
A good example of this was SuckerPunch. Most of the people that loved and appreciated what was done in that movie were women. Men, by and large, hated it. This is probably why it took so long for the WW video to make back its money. Wonder Woman is the most famous female superhero in the world...and still she struggles. I doubt a Supergirl or Batgirl film would fare any better. As long as female led properties struggle to get a male audience its going to be harder to convince the studios to fund these films.