For the record, pre-nerf, people were having discussions about Stoneskin and saying how it is too expensive to be efficient and it was good for pre-shielding and hits that someone otherwise would not survive.

Stoneskin does have a few other uses that people don't usually mention:
1. If you are stuck in cleric stance, Stone Skin retains its effectiveness.
2. It is very effective on NPCs because they have large HP pools. This mostly stops mattering after you finish the story and class quests.