I started playing during the vannila naxx event so i dont know how things were in endgame classic WoW but ive been on and off regulary since then...
In the burning crusade gear PvE gear progression was pretty strange. Basicly once you dinged 70 you first had to farm some gear to do heroics, and some heroics were hard even in raid gear.
Karazhan needed attunement and since you needed flying mount and some heroics for that by the time you were done your gear was good enough to take the first few bosses. Pretty soon you would get past the gear check 6th boss and have a great time farming kara.
At one point you would decide its time to go onto bigger things and 25man raids. Then the shitstorm would commence..... Magtheridons lair was literary impossible for a time and very very hard after fix still... Besides this you had an option to go to Grulls Lair but still even in BiS Karazhan gear it was HARD, harder even then some SSC and TK bosses which were a later tier.
Bascily many people got stuck on end t4 bosses , maybe farming some t5 and thats it.
On the other hand PvP progression was a faceroll, you would just lose 10 games a week in 5v5 and get a lot of points to get waaaaay better weapons then you could get in raids you are doing.
if you would discover the wonders of win trading, or even better just getting a good 5s comp to farm the ''10 game losers'' you would get decked out in some pretty nice gear. Back then haste didnt really exist on much gear so as long as you get hit cap via gems the wasted resilience item budget was not a big problem.
TL DR = in TBC getting gear the ''PvP Way'' was faceroll easy , while getting it the "PvE Way'' was hard and broken
In wrath it was the opposite, you could faceroll naxx and get awsome epics while it tookl probably a 100x the effort to get itemelvel 200 (19 lvls lower then naxx) in through pvp..(this remained true even later since it was much easier to kill lord Marrowgar heroic then get 2200+ rating wor weps.
TL DR (lol) in WotLK its exactly the opposite.
Now in cataclysm PvE gear progression is very hard once again, even farming heroics takes a lot of time with 1 hr ques and 3hr of wipes BUT THIS WOULD BE FINE!! if not for one thing...
PVP progression is faceroll easy once again!!! You will get decked out in awsome pvp epics 6x faster then it takes to farm up heroics with this difficulty...
So why cant blizzard balance this stuff out? It would be fine with me if i need like 6 months of 5 mans before i can raid but why would i do that when i can get much better gear much faster with more fun in the progress? Because lets face it PvP is about 10000x more fun then farming 5mans over and over again....