Its point is to be independent from proc luck. It's just there as a balancing mechanism so that if you're in the lower half where you're only getting procs an average of 40% or less than the time, your damage isn't getting smacked in the shins with a shovel. Personally I like it, there's a few different ways I use it to optimize my output or salvage a dry run of Verstone/Fire procs.

As for giving it an AoE effect as some people have suggested, it wouldn't really fit in to the AoE rotation at 3+ targets since you're losing a lot of potency by not scatter spamming and attaching Impactful to Scatter would be moot since then the damage has to be nerfed and Enhanced Scatter then probably goes in the trash and now you have wet noodle AoE spell as your proc insurance when you're running dry. It's boring I know, I wish they gave us Verblizzard/Water as follow up AoE spells that gave mana scaling up with how many targets you hit with them, to break up the tedium of Scatter.