In my oppinion,

(content for casual pve players)

One of the best additions to the game are expert rifts (5 man rifts that require normal gear to finish).

In practice: each solo player can get a lure, and it's very doable by any random public group. That group usually consists of more than 5 players. Usually around 8-12 who were defending invasion and one of them say lets do expert rift.

That is a concept for casual player, it can be done anytime, and people are easy to find, just say in lvl50 chat - group for expert rift and you will have plenty of casual - not geared people joining up looking for their uniques - (bad but still purple).

Suggestion: develop this concept more. Add more content like this which can be done by players who dont do instances (or do them casually due to lack of time). They can get rewards balanced to t1 instances. And they are in open world so everyone can join.

You can expand use of planarite to bigger extent here since players who play in the open world tend to have more planarite than players who do dungeons. Some consumables based on planarite would be nice.