I would agree with you if AoP tried to be something like a moba, a battle arena perfectly balanced for professional e-sport. However, it's not and it is not supposed to. "perfect balance" simply is not the top design goal.
The way we wanted to design the game, and I think we have achieved that for the most part, is to mix classic mmorpg qualities into a universe that is only partly fictional, which also means it's partly realistic due to real weapons being involved.
This game has to mix fictional and real components and we decided as a general rule to try to portray all real components as authentic as possible and then use the fictional content like energy weapons and power armors, the character system as well as "unwritten laws" of fallout to adapt to the set-in-stone weapon statistics.
Rather than looking at AoP's balance as a moba game or a typical mmorpg, it is supposed to be closer to a battlefield-style shooter in the sense that "feel" comes before stats. The majority of players on the call of duty or battlefield servers does not look at the stats of the weapons. Granted, I haven't played the new battlefield 4, and the last CoD's I played were the good old cod2 and 4, but the point is that each weapon in an fps has a certain feel which can be more important than stats.
As an example, the most powerful weapon in BF3 should be the m240. Back when I first got it I liked it right away and later confirmed that it had the highest damage output in the game while still having favorable other parameters like accuracy, range and a pretty good handling overall. Still, that didnt meant that the whole server was only using the m240 as their go to machine gun. Some friends I was playing with, who did not check the stats, thought the pkp pecheneg was the strongest one, just because when they tried out both weapons it felt different and they liked it more.
I never studied game design and I never looked up how "balance" is defined in the gaming industry, but what I personally would deem a good balance in a fonline game (which is a pretty unique game that I wouldnt know any counterparts to) is when there is a high amount of flexibility and variety, with as many different items as possible being useful and being actively used by any number of players, while also making sure that the game has a certain skill ceiling, allowing both casuals and pvp apes to enjoy the core gameplay of the game to its fullest.
Another example I want to bring up is World of Tanks. The game suffers from 2 problems that AoP also is susceptible to. The first one is the classic battle of simulation vs. arcade. In Wot, it leads to pretty much every single tank having guns available that were never fielded in real life and also often wouldn't even work and never got past the blueprint stage. Some tanks and tank stats are even completely up to speculation on the dev's side. Now, the devs clearly put gameplay before authenticity and after all, they pretty much have the most profitable free to play game on the market, but that does leave an aftertaste for every tank-enthusiast that would like to play tanks in their historical configuration, without being completely useless in-game.
The second issue can be seen in low tier games, with a higher number of new players. Individual tanks that would be balanced perfectly well if both teams were made up of clanwar players, seem to be tremendously overpowered just because new players dont know how to counter it and fail to see it'ss weaknesses. This problem was quite prevalent during our last session and while I could make it easy for me and just blame all criticism on exactly that point, I am trying to take every comment and suggestion seriously and think it through.
As soon as a game mixes arcade and simulation to any extent, every single decision will have to compromise on something and while AoP is a "pvp oriented" server, it is not a "pvp only" server, a forced moba game trying to squeeze every last bit of "e-sport" out of a classic '97 rpg and such, the itemization which is the 2nd most important aspect of rpg after character building, has to "suffer" in order to cater to a wider audience.