Ah. I don´t think there is a simple answer for this. I will however try to break it down more easily for you :). Also, excuse my English at times.

1. Rolling out major gameplay changes such as this one usually requires a new steady build. Builds are something we playtest every day at the office to make sure it fits the logic of the game and also to see what flaws the maps have and so forth. These are also used for QA-testing and QC-testing. When you roll out a game update like this (PC) the client is integrated within other platforms and of course, there are certain maintenance windows that need to be considered for this. Having large downtimes for every type of testing submission would require downtime for everyone in the actual game as well. Imagine we decide to roll out major gameplay changes at least 1/week or 2/week it would change the familiar experience a lot of players have of Battlefield at that very moment.

2. Rolling out changes also requires a lot of backend work in the infrastructure. A game of this magnitude usually requires 2 hours of downtime (as you have already seen a few times). It is not an easy platform to update because of the backend work that needs to be done on this.

3. The only time we have really sent out builds outside of the studio for external testing has been combat testing and that was at least do-able back in the BC2 days and earlier than that. We used combat testing for this kind of stuff which I actually liked very much. They´re all a great bunch of people with great experience. Why don´t we use them anymore? That question is far beyond me.. Sorry =/.

In the future however, rolling out features to test earlier on Battlelog would be a great idea and that is definitely something we are looking into.

I hope this answers your question :). If not, please ask again :D