I take most of that back. They are dumping the series because they're too abysmally cheap to keep the show going when Mattel once again proves how much it sucks by refusing to make a toy line since there's a girl in the cast, and making an action figure would give the rest of the line cooties or something.
Hasbro doesn't flinch at Lady Jaye or Arcee (well, at least not recently) merchandise. Playmates has had April in every TMNT line (cept the live action series, since she never popped up). A freaking Katana isn't going to destroy their already overpriced non-selling toys. They failed to make the Young Justice line affordable and accessible (there was often more plastic in the packaging), and that's what caused that to end.
What's completely baffling is that Warner Bros failed to make their biggest cash cow, Batman, successful as a TV series. They purposely screwed the show because Teen Titans was cheaper (flash animated, only 5 voice actors, and only 10 minutes of footage a week) and kid friendly enough (despite the fact the jokes are often pretty disturbing) to force down the audience's throats. There's the CN that greenlit Adventure Time, Steven Universe, and The Tom and Jerry Show, and then there's the one that cancels shows because of terrible toy lines (Thundercats), moves Adult Swim to 8 PM so we can have episodes of The Cleveland Show (which no one really liked, despite being better than FG was currently), keeps thinking live action programing doesn't result in backlashes and low ratings, and feel the need for non-animated movies that no one bothers watching anyway (Son of the Mask? Really?!?)