"Because a normal person armed with an ice-weapon shouldn't give WW any trouble. (Shouldn't give Flash any trouble either, but I won't get into that)."
None of DCU's major villains should give its core heroes any real trouble, but they do. That's not the character's fault.
"Blue Snowman" for a robot-and-gadgets-themed villain fails, and should not need further explanation for why.
"Disgruntled chemist, used to work for STAR Labs, stole a bunch of crap as she left, terrorizes city with robots that have ice beams..."
...is still a mash of way too many ideas. Simple works. And that's not simple, it's bizarre and weird. Jamming ideas that just don't work well together doesn't make memorable or great characters. The only reaction is, "What the hell is that about?" -- and if it did, maybe we would've seen this person more than once in the last fifty years? It won't click. And I can promise you that within twenty-four hours, I won't even remember the woman's name. That's exactly how memorable Robot-Chemist-Ice-Scientist-Woman is.
And that's the problem! People keep throwing random, stupid ideas at Wonder Woman, and then we watch as the next writer in charge ignores them (because they were random and stupid in the first place) in place of his or her own *new* random and stupid ideas.
Stop trying to be clever and complicated, and give us something simple to get behind. Diana's classic villains -- a god of war, a powerful Greek witch, a gigantic woman, and a woman with a cheetah-schtick (which itself is iffy because of the sacrifice-to-gods-stuff, but meh). Again, notice the difference between *them*, and Robot-Chemist-Ice-Scientist-Woman?
At the end of the day, you're still pushing a seriously lame character. Who doesn't work as a horrible mash of separate ideas. *Because* she's a horrible mash of separate ideas that have nothing to do with each other.