Usually its not, the thing is, throughout the battle, the chances of you being at full health is slim in general. If something is going to oneshot you, its going to oneshot you no matter what in general...i am thinking namely spiders where they have a tendency to double attack then sickle slash you right after.

I aint saying HP gear isnt important, but in general comparing stuff like Hope Earrings for HP and MP earrings like Onyx...usually MP gear is what makes the difference, not that crappy HP that Hope Earrings give you. Something like Pidegeon is significant enough for me to warrant getting(For Tarus anyway..for every other race i dont see why until end-game), now the +1 versions..nah. However i would also argue that you should get something else for MP as well and it would also be fine with me.