Witchfire brew's curse range

The flask was designed for DoT builds, of which most are ranged. With Synthesis coming up, there are even more ranged chaos skills that are going to be added into the game.

Am I missing the point behind the logic in GGG designing a curse during flask effect that basically has an AoE of melee range?

It's laughably small. At least 3 times smaller than blasphemy-supported curses.