The essences are mainly the level 50 things. And you can gear up from rifts. There are Expert and Raid rifts that drop loot like raids. Just not much that can be bought but that isn't different from most other games where you can't buy the best gear out there.
This is true...you can get gear from expert and raid rifts. In order to do those rifts, you have to farm the souls from the 5-man content, so no matter what you do you're going to be routed through non-rift related content.
There's still plenty to buy with planar currency at 50, it's just more focused on augments and essences and less on the gear itself.