Because I want to actually place my flaming arrow where I choose and not have it default under a single mob. By placing it you can encompass the most mobs (watch it drop under your target and then not even touch the next closest mob). And you would REQUIRE healers run into an active mob area to place a defensive spell when they are already casting it from a safe distance.

But wait! You can run in and run out without dying you say? Can everyone else?