OP, what you're asking for with gear already exists with the glamour system. When you boil down BiS gear, it's just stats. The glamour system basically allows you to slap those numbers onto whatever piece of gear you want so long as it is within your character's restrictions. Scored yourself a piece of i470 gear, but love your Cleric's robe from ARR? No problem. Glamour the Cleric's Robe over your new gear, and done. I find vertical progression along with a solid glamour system to be far superior to horizontal, especially in terms of keeping players motivated, or getting them to come back from a hiatus.

If the fights, story, loot, challenge, and ilv progression isn't enough to keep you motivated, already having BiS that you got from a 50/60/70 level raid isn't going to put your butt in there either.

New gear consistently being churned out is a very good thing. Even as it becomes outdated it increases the options of our available glamours. The YoHRa gear and 2B outfits that are so popular right now wouldn't even exist if this game worked as you suggest. That is an antiquated mmo style nearing on two decades in age.