Very few people actually hate Reimu, let's be honest. Most are apathetic and don't watch her.
The few that actively hated her were the ones that felt their BFE experience was ruined. Nobody else truly cares: most people here LARP this shit.
If anything, Reimu is so plain and inoffensive, there no reason to love or hate her. That's probably why she has the lowest audience in NijiEN.