If they didn't count as Pokémon, the only way to pull them from a deck would be through a Premiere Ball or the few things that allow you to take any card that you want. Nobody would use a card that's almost impossible to search for - relying on it just randomly showing up at the right time is way too unreliable.
As for Rosanne's, how fair would it be to be able to use one card to pull out the basic and matching LVX at the same time? Or better yet, if you already have two appropriate basics in play, to pull two LVX at the same time that match them both?
I don't have any problem with it as it is - they may not be "new" Pokémon, but they're still Pokémon - they have HP, attacks, etc. But since they are "enhancers" that can't function without the underlaying Pokémon, it makes sense that they're not a specific stage, but just floating in limbo, until they actually are played.