I never played WoW back in Vanilla but I will say this, I see the 'raiding got easier, blah blah blah' all the time in different games. There's a simple reason for it. When people first start raiding they encounter new mechanics they aren't used to - fire hurts? Then they improve, as they improve the content gets easier. It's not so much the game gets easier as that the player gets better and some mechanics are rehashed and you've already learnt how to deal with them. I agree with one thing the OP said though - I'm not sure how much previous experience in other games will help you. Skills you pick up in FPSs might be better, how well you control you character and camera will make a huge difference and will define how good a raider is.