f the game is meaningfully balanced and Fighters effectively don't bring anything to the table but "ME FIGHT GOOD," then non-Fighters must be distinctly behind it, especially if the Fighter has minimal resources to make them stronger.
Balance is not a good thing. It is a bad thing. 4E was balanced and it sucked. Every other version is inherently unbalanced. The unbalance between the classes is one of the things that makes 5E the most popular, and IMO the best version of the game.
So..."you get to play 3/4ths of a class, while everyone else gets to play a full class" is "part of the class design"?
You get to play whatever you want. I am playing in 3 campaigns right now and I am currently playing a single class fighter in 2 of them and I am having fun.
If you want to play a God then play a Wizard. It really is that simple.
Absolutely not. This is like saying, "There's nothing unfair about offering only a six-inch chicken teriyaki sandwich while all other sandwiches are footlongs, so long as the customer chooses the six-inch. Which costs the same amount as a footlong."
So you think it is unfair that Subway lets some people buy a 6-inch sub, while also allowing other people to buy a foot long sub?
A 6-inch Chicken Onion Teriyaki at Subway costs MORE than a Footlong Veggie Delite and about the same as several other footlongs. Do you really think that is unfair for subway to offer that sandwich?
These options are presented to us as commensurate. They are not equal, but they are meant to be peers. You should not be punished for choosing to play Fighter instead of choosing to play Wizard. (Or, if you prefer, "you should not be specially rewarded for choosing to play Wizard instead of playing Fighter.") But by your own description, a Bladesinger Wizard brings 3/4ths of the combat capacity of a Fighter without spending a single spell slot. The Fighter brings none of the class-derived non-combat capacity of the Wizard, regardless of what resources they might spend. That is the unfairness. Why is it okay to punish people who just prefer Fighter flavor/feel/story over Wizard flavor/feel/story?
No one is being punished.
Nothing is unfair. No one is being forced to play a fighter or buy a Chicken Teriyaki. People who play a fighter WANT to play a fighter and people who buy a Chicken Teryaki WANT to buy a Chicken Teriyaki.
Why do you say people are being punished? I am playing two fighters right now and no one is punishing me!