After I signed up, I got a message that says 'You are in. Check for the beta update in a few days.' ... something like that... Then on Xbox 360, I turned it on and got the message. I gave Xbox my console serial number in order to receive the update.
Right, you signed up and then you were selected to be part of the beta. Not everyone got immediate access to the beta. I guess it was MS' way of slowly growing the number of users over a period of time.
Here, your submitting a code and then MS selects you to be in the beta at some point.
Your certainly right that before we had to give them a bunch of details such as our console serial numbers. I guess now they dont need to gather that info from us, so they can just push out a general message to X1 users to see who wants to join.
If you prefer the old way, that's fine, I just didnt think it was a big deal.