I see it like this; They want to let everyone that showed interest in playing the game in. So all who applied and all who were let into the first 3 phases will be allowed in. So technically it's an open BETA.
Just cause Sony has a contract with SE does not mean they will give Sony the right to put the beta up for download.
1. You will need to create a SE account. So it's not just download and play.
2. They want a rough estimate on how many players they will have at launch. So codes will be needed for them to keep track of that.
Hope you all enjoy Phase 4. I will be on Leviathan (Don't look for me...). And yeah August is nigh Phase 4/Early Release/Launch, i'm so excited lol.
NOTE: Having a PS+ account means nothing to SE since they are the ones distributing the BETA not Sony. So it's just something we will have to deal with. Which really doesn't matter to US at this point since we are automatically in Phase 4 so be happy people.
you also have to consider server capacity. who knows if they will use everything they have for Phase 4 or use limited space like they have for past Phases.
i know for Phase 3 they had to stop releasing codes before they expected due to the servers being overwhelmed.