On G4 as part of E3, i saw a poll after a ODST presentation asking what players most want for a new halo game and this was one of the options. I myself would really enjoy it.
I don't think Halo needs iron sights, i mean its not COD. The game plays pretty well without them. i mean, do you expect a plasma rifle to have iron sights? The reticule is basically like an on-screen iron sight, but Red Dot sights would be half bad....
i just saw the Halo ODST trailer, and whadda ya know, theres a iron sight type thing on the one assault rifle type weapon, just wait for ODST. YouTube - Halo 3: ODST E3 2009 Trailer [H"]400 Bad Request (the vid isnt posting here for some reason so just click the link) Bungie.net : Meet Our Next Game : 10/8/2008 9:07 PM PDT (or download the video here)
I know. I've seen the trailer. It's meant to be more realistic. No, just a reasonable way for humans without implants to fire a weapon. Realism, my friend.
Halo would be so much better with iron sights because almost every other game has a sight even just a zoom. Halo would be way cooler with sights. Technically speaking...
The HUD in MJOLNIR and ODST helmets links directly to the gun you are using, adjusting the reticule on the screen of the helmet. No iron sights are needed. And i think it would ruin gameplay anyway. Halo has always been a different shooter than the rest. You run fast and jump high, you dont need iron sights, melees have lunge, snipers aren't shakey, etc. That's what makes it unique.
In some games with iron sights you just put the gun up to your shoulder and aim by the side. I believe you do that in BF: Bad Company with shotguns.