Fine. If you think it's preposterous, show how it's preposterous. Show how, with just the abilities from his class (which are, after all, what separates him from a commoner) a level 15
Fighter is more useful than a choice of D3+1
Celestial (or fiendish) Dire Tigers, D4+2
Anklyosauri, or D4+2
Bralani Azata. What do you think he's actually contributing to the party? Damage? He's not doing the damage of three pouncing Celestial Dire Tigers, all at +14 damage for smite. Soak? He doesn't have the area coverage or total hit points of a herd of bison, never mind a herd of anklyosauri. Even the Dire Tigers
each have 133 HP (allowing for Augment Summons).
And do so without reference to spells cast on him please. Those are resources granted to him by other party members in order to make him relevant. Also magic items - most of them will be the proceeds from adventuring, which could be split with the commoner instead - or just go to the more useful people. Ignore them please.
Well, let's talk through this. First of all, calm down. I myself have a tendency to get over-excited when discussing issues of balance within D&D because I have seen firsthand what happens when a druid with Natural Spell and a bear animal companion is in a campaign. I completely agree with you that fighters are underpowered in 3e/Pathfinder, but there's no need to be so aggressive about it.
Second of all, let's look at the weaknesses of summoned monsters.
1. One-round casting time. When the fighter enters a fight, he can immediately act (and if he's smart, he'll have spent one of his feats on Improved Initiative, giving him a good chance of going first). Meanwhile, the wizard needs to spend a turn casting his summoning spell. The only time he will avoid this is the scenario that he knows ahead of time that he will be entering a fight and he casts the spell with precision timing. (1/round level just doesn't last that long.)
2. Magical vulnerability. Dispel magic will take a summoned monster out of the fight, completely wasting the spellcaster's actions and a spell slot. There are other spells that explicitly counter summoned monsters, such as
protection from evil,
dismissal, and
banishment.
3. Options. A dire tiger doesn't have much in the way of options for fighting. It can charge and full attack, and that's it. On the other hand, any fighter worth his salt is going to have a ranged weapon, and he'll be decent with it even if he hasn't invested feats into it.
Now, all in all, the fighter is overwhelmingly weak compared to the options available to the other classes. On this, I agree. However, saying the fighter is useless because he is less good than a group of tigers is premature.
Even though he's not particularly strong, he has the following:
• High attack bonus + decent damage. Full BAB, his Weapon Training, and Power Attack give him a decent damage output. If you're feeling masochistic, you can do the Weapon Focus line.
• Decent defenses. d10 HD and a good Con score will give him some staying power. Armor Training also boosts his AC.
• Feats. Who doesn't want more bonus feats? Just look at what you can spend them on: junk, junk, junk, junk, and something that is occasionally useful. On the plus side, the fighter has enough bonus feats that he can be mediocre at both melee and ranged combat.
Overall, still terrible. But not useless.