First off, Middle does not equal Mediocre, secondly the answer is
because there is always a middle, it is absolutely, positively, 100% impossible to completely balance DPS. The mechanics just do not support it, there will always be atleast one class/spec that does better due to X, Y, Z factor (gear, situation, talent, etc). I would much rather be middle of the pack instead of worst and hoping for a buff, or even best and dreading a nerf.
Now, does this mean there are a few specs that are too strong and a few that are too weak?
YES. I don't think anyone can argue that Assassination Rogues are not over balanced. Likewise Arms is completely subpar (although I don't feel bad about that because we have Fury spec, and personally I hate arms).
The deltas that Xeraxis posted
25H DPS Bot should be taken with a
heavy grain of salt, however you can easily see that each class has atleast one spec that is very close to all the others.
Looking at your guilds damage meter and deciding you need to be buffed is laughable. You ignore all the major factors; such as each players Gear, Individual player skill, specific roles per fight, even luck. Especially this tier where RNG due to RPPM trinkets play an extremely heavy factor.
I'm not saying Fury doesn't need buffs, personally I think we do, but not in terms of straight % damage increase across the board until we are magically the best dps.
What we need is A) better survivability on par with other classes, B) better sustainable cleave and C) quality of life improvements such as CS not being parried, a slight speed boost after a successful Charge similar to Shadowstep, etc.
I personally don't like overly complicated player mechanics. I think most classes are in a good place as they are. I would rather see difficult fight mechanics that require you to execute your rotations correctly while paying attention to boss mechanics, instead of overly complicated player mechanics that are only really executable on a Patchwerk encounter.
Player mechanics should be engaging, not overly punishing.