The same applies to PvE and raiding. Originally you raided to beat the boss. While raiding and beating bosses you just happened to gain gear that allowed you to beat more bosses. Now it seams that you raid to geat gear and while getting gear you just happen to beat bosses. I won't say the end result isn't the same, but because of the perception shift about which part of the equation is the important one, the nature of the way the game is played has changed.
Now I won't say that all players play only for gear now, and that all players back then were totally altruisticly about the journey, that would be naive and blind. I do believe, however, that changes in design and changes in message from Blizzard have had an impact on the player base and it's perception about the nature of their experience in the game.
I would definitely argue your last point though. The main goal designed for World of Warcraft, at least at the beginning, was to provide an epic world and journey for players to experience. I would say a practical side effect of providing greater and greater challenges was the necessity for character improvement, which in a gear based game can only be provided by better and better gear. The player base over the evolution of the game has forgotten about the importance of the experience and become obsessed with the gear and the game designers have given them what they want. The toggle mode hardmodes and retread model of raiding are a perfect example of this. Each boss now provides 3 levels of gear and has snooze mode, easy mode, and medium to hard mode. You no longer beat a boss to look forward to the next new boss. Now you beat a boss so that you can kill bosses you've already killed on a slightly harder numbers requirement (with maybe a mechanic or two) so you can get better gear. The journey is lost when you start jump back to the bottom of the staircase as soon as you hit the landing.
That's a matter for a different topic though.