“To fill our pool of beta and stress test participants, we’ll be choosing dedicated players who meet select criteria from both the WoW Classic beta opt-in and the standard Warcraft beta opt-in. Participants will also need to have an active subscription or active game time on their Battle.net Account. While opting-in to the beta is the primary way to make sure you’re in the running to join the test it doesn’t guarantee an invitation to the closed beta test. We may also consider additional factors such as how long a player has been subscribed to the game so that we have the right mix of players to ensure great feedback toward making WoW Classic the very best experience for the community.”
This is the lamest excuse to try and pin it on a cash grab. Tbh this is just you complaining to complain, there is no issue. If you wanted to play classic on launch you'd have to sub before hand anyways you're still paying month to month you don't pay by week. The only way you'd lose that money is if you quit before your sub ran out later on down the road.