Group events when no one is around
There are some dynamic events which are designed for teams. They are basically not doable in solo. As the starting zones are getting less and less populated, these events often just run their course without people tackling them.
This is usually not a big issue. But there are some cases when they are. For example, in the zone I am currently in, there is a giant that attacks a town. It is pretty much an outland raid monster, and a whole bunch of players are needed to kill it (last time I saw it killed it took about 20 of us to attack it for about half an hour). When it arrives, it kills all NPCs in the town in a few seconds, and then it walks around for a while.
It would be nice to have a dynamic dynamic event that is different if there are only a few players around, and when there are a lot.
Hearts are too easy
I know, some people are never satisfied. Still, I just hate that 70% of the time I finish a heart before even getting close to the place. The reason for this is that usually hearts involve killing some monster or another, and simply going there and participating in an event will fill that heart. As a mainly solo, casual player, I'd like to have some hearts which provide me a bigger challenge or rather more fun. So far the best was when I had to play a snowball game with kids.. but that was only one of the many.
Crafting Mats rarity
The secondary crafting materials - the ones that you use for creating components which determine the bonus on the item, ie. totems - are hard to come by. This wouldn't be an issue if I would have a lot of time to play, but sadly that is not the case. Very often I find myself grinding for one kind of a resource, and I don't like that.
That's pretty much all.