The debate over if a forward assist is actually needed on an AR-15 has raged on for years and likely will never be settled. Meant to help seat a round that has not fully gone into battery due to a fouled chamber or other problems, it was originally invented to deal with very specific problems encountered in the early years of the M-16 rifle. Since then, even with the problems corrected, the forward assist has stuck around, and is either an absolute must have, or a meaningless addition to an upper.
There are multiple schools of thoughts on the matter, some relying on simple tradition. “Well it’s always been on there, there must be a reason.” To the “Well I might need it someday” to “Well that’s what I was taught in the army, even though I never used it…” Most arguments indeed either boil down to rote adherence to what has always been, or concern over the very, very rare malfunction that may require the use of a forward assist. While it is true, the sorts of malfunctions that case a round to fail to go into battery are rare (almost always a too dirty chamber), the forward assist or FA is more useful when you are trying to be quiet chambering a round. By riding the charging handle home quietly instead of just letting the bolt fly forward, you eliminate the loud noise of chambering a round and can quietly complete the process with the FA. This may be useful if you are hunting or an elite special forces operator, but odds are if you are, you probably already know what you are doing.
However, the stark reality is that you almost assuredly do not need a FA. While they are one of the most popular ar-15 accessories – they are not necessary. Online debate is dominated by a handful of anecdotal stories of using it once in some obscure military training event, or when using a poorly maintained rifle or with bad ammo. A few others will helpfully offer up some sort of gun shop wisdom about near ninja like silence when handling your weapon, which presumes a pressing life or death need for stealth nearly all of us will never face.
Modern ammo, and actually maintaining your gun have all but done away with the need for a forward assist. In fact, it was obsolete not long after it was first introduced, thanks to adopting cleaner burning ammo and requiring more regular maintenance of rifles. Today it merely complicates the manufacturing process, adds cost and complexity to an upper, and unless you want it out of an imagined need for combat operations, or rote tradition (I admit, it makes a gun look more “correct”) there is precious little reason to burden yourself with this relic of a bygone era.
The forward assist briefly served a real purpose and may have some validity in military use, but in private civilian hands, it is a needless frippery that you can happily do away with and never really have to worry about needing on your rifle.