Personally, I am for bringing casters down, many others want to elevate martials.
The main problem with bringing casters down is that certain fans will be
absolutely livid if you do so. Like, "YOU'RE
DESTROYING THE GAME, HOW
DARE YOU, I WILL ACTIVELY CAMPAIGN AGAINST YOU" levels of hostility and anger. And that vocal minority can heavily tarnish a game's reputation. That was one of the biggest reasons 4e struggled so much (alongside some issues with presentation, a terrible economic environment, and extremely disruptive and unforeseeable internal issues). Many of the complaints voiced about 4e were and still are completely false or wildly distorted, but the edition war partisans didn't care if their criticisms were
accurateor not. They only cared that the Bad Edition which Killed Fun would die--and those people won, generating a 5e that bent over backwards to not antagonize them (while still trying to sneak a few innovations in, see Monte Cook's "a little thing I like to call passive perception" and other instances, intentional or accidental, of "let's introduce a mechanic that started in 4e but pretend that it's new/do 4e things but obfuscate the connection as hard as possible.")
So, if that direction is so horrifically offensive, it's clearly not tenable. This leaves the other option as the only realistic course...but that enrages the
other vocal minority of players, the old-school fans who want Fighters to be dirt-simple (and usually all classes but Wizard and maybe Cleric too, though for many of them "all classes but Wizard and Cleric" means "Fighter and Rogue" because they don't even want more classes than that.) And those fans, while a lot easier to ignore because...well, the game's been ignoring the most vocal of them for a long time, but they still have a pretty significant influence, and the OSR movement has amped that up significantly.
Which leaves us with the sustained detente we have today. Can't weaken casters too much or you enrage an extremely vocal 10% to 20% of the fanbase. Can't enhance non-casters too much or you enrage another, almost as vocal 10% to 20% of the fanbase. The remaining 60% to 80% would most likely appreciate greater fairness between the classes--or, as like as not, simply keep playing regardless--but the relatively mild-mannered and congenial silent majority are drowned out by the loud few.