I think ARR and HW were way harder because rotations were harder, mechanics were brand new and the damage, heal and tanking checks were way harder. Even SB was harder than ShB and EW looks at the alliance raids, people still wipe to them after 7 years. I think ShB and EW aren't harder but they require way more movement and constant reacting which would make them nearly impossible with old style rotations and stats. The only healing check I can think of in EW is P10S besides that healing is pretty simple and even then after you get used to P10S its just CD you save.
I mean people still die in Hard mode dungeons from ARR and a lot of HW/SB dungeons were dumbed down for duty support. I think that the game has gotten easier it just throws more stuff at you way faster.