BoD
First boss was just a nukefest
Monkey: Fires while melee could just stand in melee clumped up
Monk+Mage: Bombs with lazers out of it where you had to run around small radius while dpsing it.
Opulence: Whole damn fight? First phase was all movement and second was take out gold far out of the casting range.
Dinosaur bosses: Whole fight again? Running from mobs, running to circles, dodging frog. Melee just does full rotation to the boss while ranged has to get to the spot. Not even talking about mages and mooninkins being decursers on that fight.
Rastakan was not too bad I guess.
Mecha was movement hell, but melee with the bombs had downtime too so yeah.
Ships: Ship phase - all movement, second phase was damn cancer for ranged stacking or cc group regardless while melee just facemelted boss in melee
Jaina - moooovement! Everywhere, beams, bombs, point a,b,c
I am not saying it was a bad raid, it was nice raid and it's what we as ranged dps do - just get on with it and plan our CDs for a time where we don't have to move with boss or around something while planning around soaking/drop off mechanics too while melee only need to plan for just those out of range mechanics and all running around does not affect them at all.
Also casters take way more of a hit when boss switch happens or dps rotation is interrupted or boss becomes unattackable. There are some melee mechanics which do suck too - Syndragosa for frost DK or bleeds for ferals (lul) which has massive impact on their downtime too but let's say a rogue or a DH does not give a shit. 3 seconds after smacking the boss they will be back in full power while ranged classes mostly have a rampup window from anything like 10 seconds to 30seconds.
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Literally all your mechanics are in the game so nothing you said has not been done by blizzard and balance is good as it is. Some fights have their issues but balance is there in general.
I have been benched because of fights only needing X amount of ranged and the rest is melee, we have benched good melee players for subpar ranged on Fetid devourer too. It's a nature of the game. You don't see raids with 18 ranged players because it is not viable and will never be, hopefully.