In ODST Bungie removed the Battle Rifle because it cannibalised the balance of the pistol; rightly or wrongly that was a brave decision, and one that I appreciated. In Halo 4 343 have thrown in every precision weapon, regardless of balance, and will let users just decide and gravitate towards their favourite one.
In Halo 4, as a result, there'll be less balance because everyone's on an uneven playing field from the off, because the mantra for Halo 4 is choice and accessibility. That's a theme that prior Halo's never bothered with, and Halo fans to this day haven't craved.
It is by all accounts a revolution, if, that is, Modern Warfare and Create a Class never happened, and the industry hadn't leaned in this direction for half a decade now.
