As far as I understand... the pack sales support the developers and creatives... but this proposal is for additional funds to spend on marketing. It's essentially an investment to help grow Splinterlands (and hopefully also Hive).
The problem is people who come in and play splinterlands need to be buying hive too. If they just ignore the chain and cash out it's not going to end well.
I don't disagree at all... but there's a good chance lots of players on Splinterlands had no idea the game was run on the Hive blockchain. You can do almost everything you need from within the game.