Let's see...
- We cut fight lengths in half or more because the modern "raiders" might run out of Ritalin...
- We had to adjust Reliquary because telling modern "healers" not to spam AoE heals for 5 seconds ain't happening.
- We had to nerf Bloodboil because we removed any complexity to threat as an "inconvenience" long ago.
- We nerf batted Gorefiend because it was too hard and there's no Weak Aura to tell everyone what button to push.
- Mother Shaz isn't remotely the same fight.
- We had to adjust the hell out of Council because players can roflstomp AoE now instead of having to coordinate raid dps on specific targets.
- Oh um... fights now are harder, really! They're not just big numbers thrown around with no real finesse needed!
Never change the "we adjust reality so we're always right" attitude, Blizz.