And on what assumptions do you base your opinion that this is not the case?
There are dynamic events all through the world, there are dungeons with two difficulty levels in game,
there are armor sets of different quality, as well as weapons.
While there isn't a gear treadmill as such, being of a competitive nature myself, a better allocation of stats on a piece of gear, one that suits my build or play style more is very much a carrot for me. I'd rather have +xxx power and condition dmg, then +++toughness and condition dmg. Across the multiple pieces of gear, it will make a fairly significant difference. Just like in WoW, people would quite happily spent their dkp/gp on a side-grade chest, simply cos it had haste instead of crit on it.
Similarly, in pvp, depending on whom your teammates are, profession wise, you will want/need a specifically itemized gear to serve the group best. It also applies to pve, if you're planning to treat dungeons like raids and do them in an organized manner.
There is carrot all over, and if you munch all that you can possibly eat, well, try the jumping puzzles
Also, check how often content was added to the original GW - whether free or paid. And then, lets talk.