You guys should learn to do a search on these boards. Then you wouldn't ask the same questions, nor make the same "arguments" that have been made before and answered before. The button is at the top of the page and looks kinda like this...
But to save you time....
The 700+ arenas were unhealthy not due to OVER population, but due to the huge base rolling hordes they promoted. Had these "hordes" actually gone head to head instead of going out of there way to avoid each other, we may still be running on large maps. Game play suffered because "it wasn't fun" being one of the few people trying to stop the horde, nor was it fun to be in the horde chasing down that lone LA7 with 15-20 of your countrymen.
EVE on-line, and other games like that may have 30,000 going strong, but its a different game with different dynamics. HTC has tried to bring the arenas back to the old size and atmosphere that they had before. Yes you still have hordes, but they are smaller and more people will get together and fight them, its not such a "lost cause" when you see them coming. It looks more like a furball witch to some looks like fun.
Squads can still get together and have fun.... which is what a squad is all about, however you may have to switch sides, or arenas to do it. Some people make there own misery by refusing to do either, and that is their problem and easily solved by personal attitude adjustments.
So basically this is what it has come down to, Arenas will have moving caps to try and maintain even numbers in arenas ( tho it still causes trouble with the European crowd due to lower numbers), Arenas won't go over 450, and we will no longer have the large maps. This is how it is, and 6 months of complaining didn't change it before, nor do I think it will now.
Love it, or leave it this is AH2. But for goodness sake don't start all this crap again, just go play the game and have some fun !