Not only that, this is by design. They want their early testers to be a small group of people who are heavily invested in the game, both mentally and financially.
Sure, a lot of people are going to be mad about being "excluded", but how many of them are going to actually boycott the expansion when it releases because of it? The ones are maddest are the ones who most want to play it and are unlikely to walk away.
There was always going to be a small group of players that got to play it before the majority of the playerbase. The only difference is the $90, and that price is well worth it to a lot of the big fans.