While yes, she IS a useless bitch, she's OUR useless bitch, one that still manages to be so cute and entertaining despite being so terrible as both a fighter and a person that we can't help but love her.

Compare that to Bitchwhore and the Three Cardinal Stooges from Shield Hero, who also have terrible personalities and are useless, but have none of the likable charm Aqua has.

Aqua is like the 25 year old kid who still lives in her parents basement
no matter how much you want to kick her out of the house
she's still your kid