Hit markers are necessary if the game's audio visual feedback alone isn't enough to convey that you are in fact dealing damage. I don't know about you, but the audio visual feedback of Reach's shields were done so well that hit markers would have felt redundant.
Hit markers also create a problem when used with grenades. Say you're trying to flush out an enemy but you don't know where they are, so start throwing nades and you score a hit that doesn't kill. With hit markers, you now know where the enemy is and are put in the advantageous position purely by guesswork. Without hit markers, the enemy still has the element of surprise, can make a tactical retreat without being seen, or hold their ground without their position being given away.
On the other hand, hit markers are useful in an online environment where latency makes weird shit happen and audio visual feedback just isn't enough.
One thing I liked about Reach was I always felt like I knew what was going on.
I kind of feel the same way about text on the screen, I'd rather know what is going on by the action I'm seeing on screen, basically show versus tell. I don't hate it, but I'd rather more intuitive and subtle indicators.
Hit markers lead to too much of a fire and forget mentality I think.
I hope Halo montages become a frequent thing once MCC is out. Seems only natural given how much easier it'll be.
I wonder what the modern day music accompaniment will be? I was going to make a joke about folk-metal till I discovered that is actually a thing and a thing that has been around a long time, so let's say folk-dubstep.