I get your point. Classic is like a chill friends and family game. However many people enjoy challenging and competitive gameplay. Retail WoW is the game with the most "complex" raid mechanics out there. To each their own.
Honestly I would enjoy the loot model of Classic better. But I would never be able to raid with bosses that have 1-3 mechanics. Give me Firefighter Mimiron and I'm more than thrilled.