People don't hate Tama in particular, if she were not introduced someone else would have been hated.
Simply because One Piece doesn't match the headcanon of a certain proportion of the fanbase on the net, the proportion salty vs the "Goda faction". It's the circle of life, if there weren't all these faction, flame and shitposting this and the other community probably wouldn't have 10% of the posts and views that they have.
I just accept it, it's normal. Personally, I don't care much about her cause Oda didn't developed much her character, she can be a good one because of her backstory, Ace, poverty etc