The Devs decided to play Skyrim after the vanilla launch as a way to relax, but after seeing the Dovahkiin 'shouting' and realizing the Guardians speak, they decided to nerf the Guardians voice box just in case the power creep from future dlc's turned Destiny into a 'shouting' match.
[spoiler]Guardian: hey Randall!!!
Randall: dismantle guardian, yeesss!
Guardian: FUS-RO-DAAAHHHH!!!!
Randall: oh fu.....
Guardian: stupid skeeter breath[/spoiler]