I agree that, at some stage, they probably had to cut her development short, but they knew the cancellation was coming long before it was made public. They could've made room to put SOME effort into giving her at least SOME depth.>You consider her a Mary Sue because of the fact that it was required for her to win her early battles.
There's a difference between "winning" and "being literally impervious to any form of damage", as well as "being several multitudes stronger than just about everything else previously established". With her armor alone, she takes the full brunt force of Lord Hater's Ship's entire offensive capabilities (and let me remind you that before Wander started fucking with him, Lord Hater was the strongest villain in the galaxy), and not only does she come out totally unscathed, but she then completely vaporizes his ship by fucking looking at it.
I could go on all day about this shit, but this sort of "I am immune to all things" shit goes on throughout the season. She's smug, obnoxious, an egomaniac, and is just immensely unlikable, with nothing to make up for it. She's never funny, the situations she puts Wander and Hater in aren't funny, literally the only reason everyone doesn't consider her the worst written character ever made is because she's waifu-bait.Lady Hater is better, anyways.