File under: "Why Butcher's Block SHOULD BE Warrior's highest damage combo"
Every tank has 3 combos. DRK /technically/ has 4. I'll rank them in order from BEST to WORST in terms of damage output.
PLD:
Goring Blade -> Damage over Time
Royal Authority -> Flat damage
Rage of Halone -> Enmity + Mitigation
DRK:
DA+Souleater -> High damage + Mana (self-heal in Grit)
Delirium -> Mitigation + Mana
Power Slash -> Enmity
(Souleater -> Self-heal in Grit + Mana)
WAR:
Butcher's Block -> Enmity
Storm's Eye -> Maim + Slashing Debuff
Storm's Path -> Maim + Mitigation
Looking at these, we can already see that each tank has vastly different priorities when it comes to which combos they use when. It's very important to note that Butcher's Block affords WAR absolutely no bonus to use it outside of its damage output. Looking at the fact that this combo allows WAR to be most effective at holding Enmity as the MT while maintaining DPS is looking at the small picture.
If we're talking big picture - the actually important things that go into the rotations of these Jobs - you'll see straight away why it would be bad to mess with these rotational potencies.
If you changed WAR's damage priority from BB>SE>SP to SE>BB>SP, you do two very very bad things.
1. You DRASTICALLY decrease the skill gap for playing Warrior effectively. Maximum DPS becomes 1-2-3-1-2-3-1-2-3, which no other Tank Job does anymore.
2. OT WAR becomes incredibly simple to maximize, where it is not right now. You point out the fact that WAR using BB is only a minor gain compared to the major loss DRK and PLD take to use their Enmity combos. This is absolutely true and is a hallmark of a B A D W A R R I O R. This should not be brought up in a discussion of modifying tank skills, because it's not a consideration when looking at a pair of tanks playing optimally wrt dps on a certain mob.
The rotations (in general) for the tanks tend to shake out as:
GB>RA>RA
DASE>DE>DASE>DE
SE>BB
And you want to take the /simplest/ one of these and make it /even simpler/ by removing the /only thing about it/ that makes it actually a thing to manage and consider.
This is bad. And silly. And not a good thing to push for.
The fact that Butcher's Block is the strongest combo is not a problem. The problem is Warriors who don't realize that dropping 20 or 40 potency here and there to allow the other tank to maintain the lead while tanking out of tank stance is a substantial gain for the raid.
If I'm playing the MT, and my WAR OT pulls hate off of me, I just let him keep it. Not my fault, not my problem. I pull in tank stance, drop an enmity combo or two to open, and then swap out and go dps in fights without serious tank checks. It's up to both tanks to manage it properly.
Maybe my opinion is shit, because I feel the exact same way about healers who pull hate off of me while I'm tanking in or out of tank stance, so take it with a grain of salt.
//PS. If you were to swap it to have SP be the highest to maintain the two-combo approach, WAR becomes the only tank in the game who doesn't have to choose whether to use mitigation or not.
//PPS. Most important thing to note re: Slashing debuff is that it's 20 seconds. Scourge is a 30s debuff, and if you shorten it to 20s, the overall rotation becomes messed up, since it'll fall off mid-combo. Goring Blade is 24s. If you changed the slashing to not 20s, you'd really mess with WAR's rotation, since 20s is /perfect/ for the way their skills all synergize with one another.