That's indeed been the goal since Wrath. Seasonal model allows for the noticeable increases of power of players like, and makes it much less of a burden on returning players as well. The TBC model of having your BiS list spread across the entire expansion, or close to it, is fine on paper as it keeps the content alive but in practice leads to burnout and having the raid do fights they're sick of just so that some guy can maybe get his Dragonspine Trophy or something. There's a reason it hardly survived the expansion.
Trinkets are the one item that sometimes carries over some power into the next tier. Unless Blizzard nerfs them like they did with Draught of Souls in Legion (but curiously not with Convergence of Fates, which was BiS for a couple specs from Nighthold to the BfA pre-patch).