Rise of Kunark supposedly just did that,
True and not true, because Rise of Kunark upped the level cap, it had to put in some new gears for level 70-80 players. That being said, of course they're the best, because the level cap was raised.
I think a better example of what you're talking about would be in Anarchy Online. When the Shadowlands expansion came out, of course everything you looted in that expansion area had to be better than what you had... and likewise with Alien Invasion... Lost Eden... it was a bit ridiculous. You spent all this time getting the best possible gear, and then an expansion came out and you had to do it all over again. It was like a chore.
On the other end of the spectrum, you could have situational based gear, like in Ragnarok Online where you could equip cards on different pieces of equipment that say... made you take less damage from a certain race of mobs, or hit a certain race of mob harder, or made your armor a certain elemental property as to take less damage from... whatever.
Honestly to me that was a lot more annoying than expansion chasing.
I did like one thing that Anarchy Online did, by introducing a concept of "leveling" gear that leveled with you and added bonuses that were applicable to your level. Some gear might have had a gear "level cap" but for the most part, it would stay up to par with you and you wouldn't have to change it very often.
I like what HJ is doing in the sense of having a gear-less system, so everybody can look how they want to, and for those who do like the bonuses from equipment, there's always the Wyr.