Do people really believe fighter and dual wield martial playstyles are currently weaker than spellcasting?
And what's so varied about spellcasting? Warlocks spam eldritch blast and nothing else, and Wizards spam magic missiles when not using hex+ray of flame because of general poor spellcaster hit rates. Druid just spams Moonbeam. Cleric spams inflict wounds in between maintaining bless.
Remind me exactly how that is any more varied than Lazael pulling out her greatsword or heavy crossbow, dipping in fire or poisoning the weapon, and then having the option of pin down, pushing attack, frightening attack, or cleave? Martial classes legit have far more gameplay variety than casters currently do because outside 1-2 spells per class the other spells are garbage, spell slots create a competition by spells for the same limited resource, and concentration makes sure you can only have one utility spell active.
I do not think non casters are weak. I think spellcasters with almost unlimited spells are too strong. They are already strong even if you rest at a more logical rate. As for the rest of what you have said, it is really a matter of how you play. Warlocks I agree don't have much to do. Wizards and even druids and rangers have many things possible. I never use MM spam on a wizard, I prefer crowd control spells and whatever cantrips are best for the situation. My druid stays ranged usually using Spike Growth and Entangle rather than Moonbeam, and only shifts into spider form if I need extra Web casts. I do not use the other forms. My ranger uses the same spells and a crossbow, not dual wield. I don't play cleric because I don't need the extra healing but if I did, they certainly would not be spamming Inflict Wounds because it is melee and I prefer ranged on everyone.