I think we should not get kicked out of the server if the Resource Pack doesn't load. I still would enjoy running around fighting and catching Pokemon. It's not the Resource Pack that makes this a good server. It's the game play. That makes it a good server. All I need is the name of the Pokemon and how much life they still have.
You can't really have the game play if the pack didn't load. You won't see much of anything which takes away from the entire experience.
But it should be the player's own choice to play with or without resource pack. It would be their loss on their experience in the game. But they should still be allowed to play the game.