I don't understand a lot of the discussion in this thread.
As near as I can see, all of the incarnate abilities can be accessed solo. It may be slow and take a while, but it does definitely seem that it can be done.
Now, the way I see it, there really isn't any problem with the game devs making more group-centered content. I myself solo the vast majority of the time, but sometimes it's fun to get in a group.
It would be very nice if they'd also work on some solo (or at least soloable) mission arcs for incarnate content. But you can't really ask for everything in every content release.
