Balance, Homogenisation and Encounter Design: The Problem.

[linay]

Also I've seen plenty of wipes over the past 5 and 1/2 years in EX and Savage fights where the group could do the mechanics perfectly but they just didn't have the dps to kill the boss

That said, sometimes doing mechanics perfectly means doing it while keeping up high uptime. It's not really doing mechanics perfectly if you don't do anything (or do less than you should) while "doing" the mechanics.

That isn't on the players though. When jobs are this imbalanced, the fault lies squarely on the devs for allowing it to occur. The players are simply taking the jobs which best help facilitate a clear. You can argue Ninja is perfectly viable but when a 20% Monk is better than a 50% Ninja, well...

And just for reference sake. You don't see this happening with the tanks despite Warrior being clearly weaker than its counterparts.

It is on the players when there is nothing in the game that tells the players to take that 20% monk over that 50% ninja. That is purely player preference. Sure, that preference is influenced by the state of the game, but it is still a preference rather than the game telling you that a ninja cannot work on so-and-so fight regardless of how good the player is.