That doesn't take away from the fact that until Reach, it was easy to tell what they were "feeling", and a lot of the time you could tell what they were doing just from the sounds they made, and sometimes even what they were "thinking", for example if they were panicking, or if they were laughing maniacally, or if they said "grenade out" or any of a hundred other lines. Elites and Brutes in Halo 2 and Halo 3 (and Brutes in ODST) would do a lot of this too. It's not about being like a human, it's about giving the impression you're up against something with some intelligence. Bungie tried to give them their own languages in Reach and still accomplish that, and they did a little with tone of voice and probably a few common lines, but even just changing the language took away a huge part of their character.

: While Knights are also somewhat humanoid it's their insect-like
: characteristics that I like most. Do insects think and react like humans?
: No, but their intent can at times be very easy to understand and they can
: do it without uttering a single word. More insect expression would make me
: happy.

That's fine, but it's kind of pointless if players can't understand it, so they should be things that are fairly universal, or are completely consistent and kind of repetitive, or they should include some kind of guide to what different postures, expressions, sounds, etc. mean.