Lets say they go with your idea. A month before release there is an open beta that goes until release date:
- It takes work to create a beta so the version of the beta is always a poor representation of the game. The beta version is always at least a month or so older than the current version that they are working on. So the users are likely identifying bugs that have already been addressed or fixed.
- Lets say the beta is released on feb 1 and the game is released on March 1. The only feedback that will be in a day 1 patch is likely to be feedback from the first 2 weeks because it takes a few weeks to fix the bugs and submit the the patch for cert. So most of the feedback wont be in the retail version of the game until the day 30 patch.
- Also as you said, EA will never have an open beta 30 days before a game is released. To many opportunities for people to record and upload bugs/glitches online and lead to negative press. That will absolutely step on their promotion.