I'm not sure how much they could buff it, as it's Frost's hardest hitting ability right now.
Note: This is from testing a 100 template character with the basic 680 starting gear on the ptr, and obviously no artifact. Still, Glacial Spike does by far the most damage. The only thing that comes remotely close is a Freezing Fog Rime-proc Howling Blast, which does about 70% the damage of a Glacial Spike. So I don't think it's damage is that bad. The straight line is weird though. I think it would be better/cooler if it was a straight line that went out from every direction from you. Maybe have to nerf the damage a bit if they did this, but it would be more useful.