That and Japan's idea of lesbians is DRAMADRAMADRAMA. Just remove the SPICE scene in episode 1 and you've instantly got a recipe for epic. Hagino and Mari get it on, repeatedly. Tsubael interrupts. Mari learns about the invasion and insists that Hagino stop it. Things go from there.
Yuri anime with drama/action always go wrong because Japan think to have girl-girl romance, you need FUCKING TONS OF CHARACTER DRAMA AND NO PLOT. If they could just accept that Hagino is from a race of all-female squidpeople and Mari is the gayest thing since Himemiya Chikane, it'd all be okay.