From what I know in my own experiences it's a problem that goes way back to early RP in Secondlife. The problem was that Sims would create a specific theme that had no place for furry avatars, but the furries would get all bent out of shape about this and instead of respecting the environment the sim owners were trying to create they would gang up and harass the sim. Sometimes this even involved using sim crashers to keep everyone on the sim from being able to enjoy the environment. This escalated over the years, and when Sim owners were finally given the rights to manage their own estates and ban whoever they wanted without having to call in the linden police, the prejudice was already there. A lot of sims will note "No furry avatars, it doesn't fit our theme" but you still see furry avatars show up on the sim to grief those people because they 'think it's funny'. This is why there is so much hate as you put it. It's a two way street, but there's a few bad apples that leave a bad impression for the greater audience. Throw in that the RP community in SL is pretty small and gossip travels at light speed, what happens in one sim is known all over the RP community in SL before the day is out. The repeated offenses of furries disrespecting, griefing, and disobeying rules continues to reinforce the sim owner's concerns with allowing them to participate.