Point at the monsters and shoot. This bears no resemblance to rocket science.So Multishot is bad because it doesn't work when you try to use it like you would use Chakram or Ball Lightning?
One ability works considerably worse than two alternatives. In open terrain, I use Chakram. In more narrow confines, I switch to Ball Lightning. Tried Multishot in both situations, and it performed extremely poorly in both. Not to mention the total requirement for using Fire At Will. If I wanted to switch to a different Chakram (Serpentine, Razor Disc) or Elemental Arrow (Ice Arrow, Nether Tentacles) rune for certain circumstances, it gives me better circumstantial performance without the cost of those abilities DOUBLING. Multishot has no options. None of the other runes available give even a fraction of the performance boost that would justify a 40 hatred cost. You might have had a case for the discipline regeneration rune, but not now that Smoke Screen has been hugely nerfed.