I feel the need to rant. Just for old time’s sake. Sorry. 
Sangheili in multi-player have been a part of Halo for 9 years now. They were a part of almost every custom-, matchmaking, or even forge game I had ever played during my time with this franchise. I liked my Sangheili. Games feel… Wrong without it. I’m relatively sure every Sangheili player can relate in this regard. And I was quite upset when they were not included. It removed an important part of multi-player from the game for me. The reasoning behind it was upsetting as well.
I fail to understand why they were removed from Halo 4. Why were Sangheili be removed? I don’t actually believe 343i told us. We heard through IGN first. They never actually told us we wouldn’t be able to play as a Sangheili formally. Linking back to a post I made 4 months ago, had 343i told us themselves and done it in a manner that would have been sad and apologetic, I would not be as upset about the entire situation. But they didn’t. Making our plight seem unimportant or simply a side-show, as it has been seen as ever since by 343i. We’ve never had a response. We’ve never been mentioned. Not from what I have seen.
The thinly veiled excuse of “multi-player canon” as a reason for their removal was seen as bad mere days after the announcement was made. If Sangheili were not possible, why not give clear reasoning? Since Halo 4’s release, we have seen the Flood, Monitors, and these new “mini-Spartans”. If these things can be created within Infinity’s simulations, and within canon, why can’t a Sangheili? The holographics of Infinity could recreate a Sangheili layered over a Spartan-IV in the manner of Flood, or in any other such way in the manner of Monitors and “mini-Spartans”. Even without the use of simulations, it is still possible in canon with the use of real Sangheili. The alliance between the UNSC and Thel’s faction should still be in place, and relations should have progressed in the past 5 years. Linking back to mine and Raviruga’s posts god knows how long ago and Cobra’s a little while ago, Usze 'Taham should still be the Sangheili liaison to the UNSC, and could have organised joint UNSC-Sangheili training missions. Why could this not be done on Infinity? Humanity’s pride? No. There is no reason 343i could not have created a scene in which this could have been done.
No. Multi-player canon was not the real reason for this change. Sangheili can be implemented inside it, as pointed out above. I struggle to comprehend the reason. Did 343i run out of time? No, that is not a valid reason. They should have made time. Split the tasks. Move programmers from creating all the unused/redundant armour models to creating Sangheili. Though I am not a manager, and I do not work for a game company. But lack of time is a bad reason. The conclusion that I have unfortunately gotten to is that 343i simply did not care about it enough to include them. Though I am naturally pessimistic. 
This non-caring attitude could have been brought upon for different reasons. My first thought was about cost. Giving a task to a team is costly, and each task implemented is money off the company’s budget. But I’m not sure I want to believe that. A company that “listens to their fans” would allow this to be implemented and take resources from a less important or redundant task if money was a problem. My next thought was whether it was unimportant in their eyes, which was again unbelievable, if 343i wanted to give an air of “listening to fans”, as this thread had been here since March and was huge within a month. The only logical conclusion I could come up with was that they simply didn’t know that our views existed.
Linking back to a previous post, many people do not understand my need to play as a Sangheili. They say “there’s no difference!”, but there is. I’m sure other Sangheili players will agree in this regard. I’ve been a Sangheili player ever since I laid hands upon a Halo 2 at a friend’s house. I would be quite insistent that people change their game-type if it had no Sangheili enabled in Reach. I do not believe that 343i knew of this view. They probably thought that we wouldn’t mind that Sangheili were removed once we saw the sheer amount of armours in 4 and Dominion. No, I don’t think they understood the inclusion of Sangheili that Bungie had implemented, nor the reasons why we liked to use them.
Now this thread has gotten to the size it has, I do believe that we have a much higher chance that Sangheili will be implemented. There’s no way that this thread hasn’t been noticed. I’m upset about our position, and I have been ever since it was announced on IGN. But I do believe that their removal was done in good faith, with them not realising the effect of it. I have faith that they’ve realised their mistake, and I am glad. All I wish for now is that we get a response, of any kind. It would give me piece of mind, which really should have been done in Halo 4. 
[/rant] Sorry guys. It’s been a good few months or so since I’ve ranted, so I built it up specially. ;D