Each expansions "buffs" made talents and damage for abilities strong so it scales up for the end game. I'm sure you have at some point tried old content with "new content" gear for instance you can get Wotlk gear at Lv68 (including enchants etc) I'm sure that made stuff easy leveling there right? Its the same for Lv 78->80 it makes stuff really easy right.
Current talents/abilities are made to be "optimal" at Lv 85, so before that your abilities are somewhat overpowered. Blizzard even SAID in a blue post (before cata) that they may be removing/making harder to obtain some "hard mode special content because cata talents makes things way too easy".
Anyway I do agree with you I wouldn't want WoW heroic raid style stuff in FFXIV, the difficulty difference between FFXI/FFXIV and Wow content is miles apart, and would cause alot of rage most likely (that and the FFXIV team probably isn't used to making such content and would be all kinds of wtf going on).
I liked the ffxi "endgame" because its relaxing (and or a wipe fest but still relaxing!), I can sit and eat dinner, watch a movie on the side or something while tanking dodore/ buffalo/tiamat/niddhogg etc (or dpsing) in wow... they don't happen ;/