Then I'll ask you, did you hate the idea of Robin joining the crew?
Sugar is in many ways similar to Robin - they both fought on the enemy's side, their abilities seemed somewhat unstoppable at first, and their personalities aren't even far from different. Just like Sugar, Robin seemed cold, as if she didn't care about the people around her. She smiled as the rebellion in Alabasta clashed with the royal army. Basically, she was the ideal partner for Crocodile, up to the last chapters of the Alabasta arc.
Now, what's so different about Sugar? We barely know anything about her; not her past, her train of thoughts, nothing. No one knew anything about Robin when she first joined, some even hated the idea of her being a Strawhat, just like you with Sugar. Then her struggles, past, and true personality were revealed, and before we knew it, she was many people's favorite crew member.
Sugar even started to act off when the dwarves cried out for the people, as if she felt sorry for them. It was around here when people started to think of her as a possible candidate, and I don't blame them for it. She looked at them with perhaps the most depressing face I've seen in the series. You can interpret it the way you want, but she's definitely not day dreaming about grapes.
Regardless of my personal opinion about the matter, I am in no way saying she'll join the crew. I have no idea if she will. However, denying the slighest possibility of her joining is ridiculous. From what I've seen and read, I believe her chances are higher than most others. I even find it weird how people consider someone like Rebecca or Kyros the next member.