I see a lot of complaining about AR's being overused, and many jokes about this game being AR 514 and the like. So I'm going to explain why ARs are so used by the game.
First, familiarity. All of the suits use the AR as the base suit new characters get. A lot of noobs, not understanding how skillpoints work, will invest in upgrading this AR so they can be more effective. By the time they learn how sp works, they're already invested in the AR decently, so why let that skill go to waste? Thus, they continue using it.
Second, versatility. Let's look at the variants of the AR. the AR variants cover the spectrum from close with the stock AR to mid range with the TAR. Now, let's look at map sizes. I will bring up as an example a skirmish battle map, since they are the largest currently available. They have a dash to the closest objective of about 200-300m with the contested (middle of the battlefield) objectives usually within 200m beyond that. Especially with the urban environments these objectives, guess what weapon can cover the vast majority of engagement ranges? Now not every AR can cover all these ranges at once. But the vast majority of engagement ranges can be covered by the AR or one of its variants.
Third, is lack of variation. In the close to mid range category, the AR has almost no competitors. Only approximately half of Dust content has even been released, and when it comes to the AR, the only other competition it could have is the assault scrambler rifle. The scrambler rifle does have a similar range, more mid than close, but similar range, but it requires lvl 4 in scrambler rifles to unlock. The base scrambler rifle is a single shot, mid range weapon, which is what most new players think is the only type of scrambler rifle. Especially at the typical engagement range outlined in the second reason, and partly because of the first reason, they never see this variant, which for some would actually be more in their playstyle.
Lastly (of reasons I can think of before I post this) is reputation. Let's think like a FOTM player (or continue thinking normally, if that's your thing.) With all the posts about this being AR 514, and how OP ARs are, and how everybody is using them, what do you think I want to spec into in order to have the best k/d ratio?
Now, what does this mean? The problem is not with the AR, one cannot blame the knife for being OP at cutting things, which is it's job. The same is true of the AR. It is a fairly (with exception) balanced weapon, the problem lies within the maps, the starter fits, and the lack of other options. As to the first one, I believe opening up the maps will go a long way to alleviating this problem (this would need to be done carefully to avoid making the game Sprint 514, but that's another topic) because it would make a larger base of weaponry more viable depending on your location on the map. In the buildings, the AR would still be useful. But out on the larger plains areas, the sniper and AV would reign supreme over the AR. As well, giving the player a wider variety of options wouldn't mean that the AR family would be used less, but at least there would be variety in the type of AR utilized. I think seeing different weapon skins would go a long way to assuaging people's feeling of AR 514, even if subconsciously. Tying into this, once all the races have an AR, giving the starter class a weapon based on their race would give players a wider range of weaponry to test out, and more importantly, different weapons to skill into, adding some variety to the game. Lastly, if these changes were implemented, then the reputation of the AR being king over all comers would die down, and FOTM players would move on to something else (likely the Flaylock, if CCP doesn't fix it soon tm. (Don't know how to do the trademark symbol.
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Now I'm not saying that all ARs are all balanced perfectly. The TAR definitely is/was OP with a modded controller. However, ARs as a whole are by and large solidly made. It just so happens that the situation where the shine the most is the most common situation encountered by a large margin.
Forgive me for the wall of text, and maybe CCP will implement some of the suggestions mentioned in this post.