When you mean range, you mean SMN and BRD right?
Because any monk, even a severely gimped undergeared monk can kill the top BLM. BLM needs to cast to hurt you. Any melee attack interrupts their cast, including auto-attack. They also need to face you and keep facing you, and can't turn while casting. They will always lose against you. Always (Pretty sure you can survive 18 Scathes and kill em before they kill you with those 18 Scathes).

PLD have their ups and downs. WAR better due to overpower requiring no targeting and they can just spam it. DRK has similar AoE. This means Node Superiority, kill superiority statistics - faster adrenaline.

Yes, melee would be even more devastating with no need to position themselves.
Let's not talk about LB 1-shotting anything, meaning you have Faster kills meaning more gauges thus more kills, etc etc until 2v1 happens.

AST are technically invulnerable. It's ridiculous. At least SCH you can CC their Faerie and then kill the Scholar when they run out of Aether stacks. AST? Not so much.

There's a lot of glaring issues. But it's definitely not melees/PLD that are the main culprit here. The whole system is skewed.