Here's a post I wrote on bloom in Reach a while back and why I hate it in any form in Halo games.
"One of the most palpable and controversial additions to Halo Reach has been precision weapon bloom. As your rate of fire increases, the deviation of your bullet trajectory also increases. To understand why this is problematic, we need to first understand what the role of a precision weapon is.
Precision weapons have one function that is inherent to their very nature; they are supposed to provide the player with a reliable weapon that demands and rewards accuracy. Bloom is the antithesis to both of these tenets; it reduces reliability and reduces accuracy.
But! You may scream; the weapon is perfectly accurate and reliable when you control the bloom. I agree, however, there is one major problem; shooting while bloomed does not ensure you will miss. In fact, shooting with slight bloom is preferable the majority of the time due to the rate of fire benefits. Suddenly, our precision weapon has neither precision nor reliability when used most effectively. At that point, it is not longer a precision weapon but it still rewards headshots, which are now almost completely random. The outcome of two players aiming exactly the same and shooting exactly the same is random, which is unacceptable for precision weapons.
The role of bloom is to punish players for missing shots and spamming the trigger. The more you miss and spam, the less accurate your gun becomes. While this is a decent principle in general, it requires weapons that can kill quickly to operate properly. In Reach, bloom doesnt just punish missed shots, it punishes everyone because it is literally impossible to kill someone with the DMR or Pistol before bloom becomes a factor. What this means is that in every 1v1 encounter, bloom is going to be the determining factor; you either spam your shots and play the odds, or you pace your shots and risk the other players odds. Either way, chance is what determines the outcome.
When bloom is applied to weapons that kill rapidly, like in Call of Duty or even the Reach sniper rifle, it begins to make sense. Accurate players can kill enemies before bloom becomes a factor. Players who miss shots get punished with bloom. When bloom is applied to precision weapons that kill slowly, like the DMR and Pistol, it doesnt work because every player, regardless of accuracy, is punished with bloom.
With such lengthy kill times and bloom playing such a central role, many players have fallen back on the argument that controlling bloom is a skill. Controlling the bloom is not so much a skill as it is a risk assessment and risk tolerance test; essentially risk management of a randomize outcome. A skill implies that you can increase your aptitude with experience and practice, which is simply not the case with bloom. Because of the inverse relationship between accuracy and rate of fire, you will never be able to rely on non-random elements in a firefight. As I pointed out earlier, even if you pace your shots completely, the enemy may choose to spam: chance enters the equation. Unless both players begin shooting at the exact same moment, it will always be beneficial for one player to spam.
There is no perfect bloom level that a player can fully rely on; if you choose to shoot at a medium pace to marginalize the effects of bloom, someone could choose to shoot at a rapid pace and beat you. There is nothing you can do to change that. That is not skill, its accepting a certain amount of randomization. That is never good for a competitive title and is unacceptable for the primary utility weapon.
Regardless, lets pretend it is a skill. Does that mean that the skill value of controlling bloom is greater than the skill of controlling precision shots? The punishment for mismanaging bloom is not as severe as it is for missing a shot; mismanaged bloom, no matter how extreme, still gives the player a chance to win the fight. Missing a shot with a true precision weapon leaves no chance in the equation. If controlling bloom is a skill, its a secondary skill at best because you can never master it to such a degree that you can fully rely on it.
Not only does bloom destroy the basic function of Reachs precision weapons, it encourages players to bring random chance into every battle. While bloom isnt inherently unacceptable, it is when you combine it with the kill speed of the DMR and Pistol. Random chance should never be a fundamental aspect of Halos utility weapon, and removing bloom is the only acceptable solution for Reach to regain some competitive merit."