Then we gotta agree to disagree, because I ask for evolving in my First Person Shooters than sitting on their laurels.
Sure, you can use the needler/etc. in Halo, but why would you? The kill speed is slow, it doesn't take out so many enemies in quick succession.
Really, though, my BIGGEST issue with Halo's campaign is that it's just plain boring. There is nothing exciting (IMO) going on. Again, you don't feel like "you're in a war." Bungie never attempted to force the player to go into stealth:
There is 50 enemies in an area listening to the commander. Shooting any of them is a guaranteed death.You have to sneak past them to get to the next area. You may/may not have active camo...
THAT, or anything in variety would spice up Halo. It doesn't have to have destructible environments (but it would be nice, IMO that's where the genre should go next) but it does need less "go here, sit here for the dropship to come, kill them, move to next area, wait for dropship..."
Note: I haven't played Reach yet. But from what I've seen it's similar to 1/2/3/ODST's campaign which is a bit disappointing as I expected a huge amount of covenant to overrun you.