>>56312199I think the hate comes from being second-class tools, like in traditional JRPGs where the player is given the option to choose one of several exclusive weapons/items and the rest are removed so as not to break the game, so the player settles for giving a bootleg version of those weapons to their party.
Transferring that to Pokemon, the Starters are that special weapon and the monkeys are the replacement for those starters that you couldn't select for your adventure, but as the adventure progresses, these aren't at the level of the better tools you find and in the end you end up throwing them away.
For me, the monkeys are a good idea, but half-baked, the developers realized this and in later installments they started giving you a second starter.