>>43267311You have to understand that a high level fighter isn't just 'Shitslappy McSlapshit' the human blender that quad wields double headed axe-staves.
Sure, a cleric or a mage could stand at the front and dish out damage. But the fighter is the best at this job, accept no substitute. You wouldn't ask a cleric to pick a lock, you wouldn't ask a fighter to cast spells and you wouldn't ask a mage to stand at the front of the mosh-pit and get his teeny tiny bones smacked around.
Examine the Fighter and all Fighter flavours;
The Fighter is a front-line warrior. He can be a whirling dervish, untouchable and deadly. He can be a stalwart shield, a megalithic structure through which no malevolent force may find purchase. But above all else, he is considered a consummate professional in the art of war, tactics and strategy.
The Barbarian, a hard hitting mess of fur, teeth and blood. She's perfectly happy tearing her enemies limb from limb with her bare hands or any of her oversized weapons. But a leader she is not. She's quite literally a lone wolf.
The Paladin is a virtuous champion of rightousness and good. His zeal makes him slightly better than a fighter when it comes to leading men, and often he's considered the face of the party (thanks to the charisma min-max) but his concept of law and order might leave him at odds with the mercs and hirelings that a fighter would have to manage.
Long story short, a fighter is the frontline because everyone else is substandard when it comes to being frontline. The fighter is therefor the most important part of a party. Everyone else is his pocket bitch for problems that can't be smacked with a hammer or yelled at. Accept your fate.