Well we all obviously enjoy the game, we just praised it so much that there isn't much else to praise unless it's new content. It's great that we got a new map but the game has bigger problems that they don't even seem to address as an issue, the menu lag for example is still present after multiple patches.
Something as simple as using menus is practically broken, of course I'll complain about it because if not then it won't ever get fixed (heck it might not anyway...).
You are right though, people do focus more on the negative, but I do think that's usually done because of general passion about something, even though it usually looks like lashing out on innocent people.
Battlefield games just have a tendency to do 2 steps forward 2 steps back.