While the Jetpack is indeed a lot of fun to use, it does more harm than good in the long run and I feel that it is an unnecessary addition to the Halo franchise.
The Jetpack single-handedly allows players to bypass one of the fundamental facets of Halo gameplay known as Map Control. This term refers to the act of <mark>a team</mark> maintaining possession of a strategic area on the map. This area often gives the team access to power weapons; however, its main purpose is to afford players a safe way to defend their own base and trap the enemy at theirs, thus preventing them from advancing. This doesn’t necessarily mean Map Control = Spawn Trapping, but the latter can be the result of the former. That’s for another thread. Also before this paragraph is done, refer to the highlighted portion. It takes a team to control the map. Onto the main point–
Let’s look at a map like Asylum. The team who wins is usually the team who gains possession of the Ring in the center of the map, which allows them to defend their base and trap the enemy at theirs. These setups are not impossible to break and it takes a team who knows what they’re doing to maintain it. But along comes Jetpack, allowing the losing team to blast off like Boba Fett into the air and rain nades on the players in Ring. The purpose of controlling this area has now been diminished, as it is no longer a safe area.
Though it is indeed easy to kill jetpackers (the bad ones at least), their death in mid-air doesn’t make the thrown nades, needles, or fired rockets disintegrate. It also doesn’t excuse the fact that these players were able to gain height advantage that they didn’t work for. Imagine being able to Jetpack to the top of Construct or around Lockout–these maps that otherwise played well (rewarding proper map movement and punishing mistakes) would be ruined by the Jetpack. And the worst part is, maps designed around the Jetpack (Sword Base) not only end up bad in and of themselves, but they become worse when Jetpack isn’t around.
Maps are designed with player movement and opportunities in mind. Designers want people to move around a certain way and they want certain paths to be used. Jetpack takes a middle finger to the designer and gives players an advantage they didn’t work for. What’s the point in lifts, ramps, or ladders if people can just fly up?
If Jetpack remains the same as it was in Reach, it will be the most abused AA because now people wont have to choose between vertical or horizontal mobility. <mark>The only way I could see Jetpack working is if it functioned like the Gravity Lift from Halo 3 or like a powerful Thrust of air to propel the Spartan upwards (jump-pack)</mark>. This way people aren’t flying like 2 ton birds and it’s of strategic use.
If you need further convincing, play Uncaged. If you don’t use Jetpack on that map you’re doing it wrong.
TL;DR: Jetpack bypasses map control, disrespects map design, and gives unfair advantages to players who don’t earn them. If its niche is to be filled it needs to be a burst of height rather than a controllable flight.
EDIT: Apparently there’s a similar thread with more discussion. Seems to be the topic for today. As long as the point is made I am content. 
