I feel like some of the issues with the 5E Fighter are already being addressed with the enhanced Backgrounds coming in Dragonlance: Shadow of the Dragon Queen this November alongside with the Free feats things. The Squire/Knight feats allow your Fighter character to become more melee focused a bit more, with the Battle Master going hog wild on that aspect. When it comes to the Bonus feats, that you choose, a DM could customize the list that a PC can pick from based upon the background chosen. So, the Skilled Feat could be a potential choice that one would pick if they wanted to make sure their fighter got a bit more skills in their kit. A Fighter with the Entertainer background could have the Actor feat as a possible choice selection, so on and so on. (Of course, that would be both the DM and the player would probably have to work out some ideas on what possible feat list selections would be for such a thing.)
Perhaps not the be all, end all hot fix, but some of the issues present can be fixed/patched by work arounds such as that. As for other things, like the Indomitable feature working the way it does, instead of being a Legendary Save type fix, well yeah, I can see that. And then we don't even know how most Classes are gonna be changed/modified when 2024 comes around. Perhaps Indomitable will get fixed by then
And yes I'm fully aware that the Knight of Solamnia background is unique to Dragonlance, but nothing is stopping ya from refluffing the background to something more appropriate to your campaign, unless your AL or your DM is fussy like that.