This is the reason why it was removed:

Halo 4 could have had a stasis gun. Or a "grapple harpoon." But these weapons were taken out in an effort to make the game more accessible and less sci-fi.

Franchise creative director Josh Holmes told GDC audiences that "when we started out, I was really pushing the team to go in a very sci-fi direction. I wanted to embrace the sci-fi nature of the enemies and explore concepts that were outside the box for Halo, things that you'd never seen before in the Halo sandbox."

Unfortunately, the more sci-fi concepts didn't resonate with players. "What we found as we were testing these weapons with players, the really deep sci-fi approach wasn't relatable. As a result, they weren't really gravitating to these weapons."

"It really sucks when you're making new weapons and no one wants to use them," Holmes added.

Eventually, 343 Industries had to make sure that all the weapons in the game could be understood by players immediately. For example, the scattershot is "at it's core, a shotgun," even if it does disintegrate enemies. The other weapons that made Halo 4's final roster all have immediately understandable real-world counterparts, like a sniper rifle or an assault rifle.

"One of the barriers to entry with Halo is that it is sci-fi," Holmes pointed out. "It's had a very steep learning curve that's turned off a lot of players."

So....thoughts?