To me an alpha or a beta is used to take feed back on gameplay, mechanics, environments, bugs, etc. Something this close to release can be nothing but testing the networking side of things. For a march 11th release the game will have to go gold in less then 30 days. Even with a day 1 patch, changing anything with the mechanics of the game would take too much time.
This is only to test their servers to make sure they are ready to go on launch day. Nothing more.
Having worked on actual beta's and even pre-announcement projects. These are not "betas" to me.
It is NEVER too late to change the game play in this day and age. Example: Forza 5. They completely changed the game play a month into the game's life cycle! Made cars MUCH cheaper, made earning money MUCH easier, thus changing the way that everything is earned and unlocked and changing the whole experience.
They didn't change how cars go around in circles, but they changed the whole game. In the same way, they aren't going to change how guns go BANG in Titanfall, but changing the unlocks and leveling system completely changes the experience.
Obviously people constantly confuse the terms (even you put in the title it was a Beta
just to catch people's attention as EVERYONE has heard the term Beta testing) but I think you are hung up on the Alpha testing of the deep innards of the game and the later testing (Alpha again) of the leveling, unlocks and servers.
I think they do these tests to show that people can't instantly exploit the system and it allows them to restart everyone's stats if something DOES go wrong without the whole world throwing a b*tch fit. The only reason people didn't throw a fit about Forza was because they didn't make anything harder; only easier.