Part of the issue I think, is pretty much that everyone got access to Fighter goodies, making the Fighter weaker because while he got more goodies, he got nobody else's.
Oh I agree, uniques is what sells the class. The easier it is for someone else to obtain your traits, the less powerful you really are. Like even the Monk grants two three bonus Feats, better saves, Evasion, and a couple other abilities as a 2 level dip. But McGeneric? Have two bonus Feats, and some BAB/HP like it makes up for it.
Yeah.... no. Do I look like I play 4E? - *cough* Low blow, low blow. - How about I buy extra Feats and play something with character?
McGeneric. Right there is a third of the Fighter's problem. Like the other 3 iconic classes, the Fighter is all about being generic and covering one fourth of all fantasy archetypes. Unlike the others the Fighter wound up designed by subtraction. Rather than giving the Fighter the ability to do anything any fantasy warrior could do, they limited it to what every fantasy warrior could do. (Swing stick, repeat.) The exact opposite design principle from the all-mighty Wizard, but a bit similar to the Rogue. (Who fair better than the Fighter as they do not suffer the third problem.) D&D practically invented the fantasy priest, so it being all inclusive and generic is a bit of a given. As the class is shaped like itself, sir.
The third part of the Fighter's problem is, indeed, that its abilities form the basis for
everyone's abilities. There is literally nothing that a Fighter can do that
every other class cannot also do. Fighters do not even get token advantages in enacting the vanilla combat options, let alone a worth while ability that spellcasters are barred from, such as the extra weapon attacks from 2E (ect.). It is this problem that makes the Fighter suck as hard as it does. It isn't allowed to do anything that someone else cannot do.
Ever. (Well the Fighter-minus classes manage to be worse due to being limited specializations of the Fighter, but that is either due to lack of imagination or being NPC classes. [Commoner, Warrior, Samurai...])
In older editions the Fighter at least had an action advantage. (That, yes, it shared with the other two warrior classes. Those classes were intended to be rare, and in less direct competition with the Fighter. Plus, the ability requirements would typically give the Fighter better combat stats when rolls were equivalent.) Come 3E, that advantage swung the other way and spellcasters were given a massive action advantage over the Fighter. Exceptional Strength was removed, while Polymorph type abilities gave casters the Strength advantage. Weapon Specialization was watered down dramatically, reduced from a bonus attack to a pathetic +2 to damage. Yay. Add to that that the Fighter's supposed class ability, Feat access, gave out piles of pathetically weak abilities that took a load books before any real synergy between them developed enough to make an extra 5 feats meaningful, let alone 11. To make matters worse, spellcasting feats tended to be vastly more powerful than combat feats and scaled up with levels rather than stagnating. To add insult to injury, Fighters have the most abysmal skill list in the game, but at least they have Warriors to commiserate with!
Plus, still no Familiar.