I can ski around it to a point, but particularly with wide skis, base convexity tends to be an issue. If you only ski soft snow, that may not matter, but if you want to be able to edge effectively—even if it's just on the sketchy, still-frozen traverse to get to the aspect in the sun—having a base that's at least close to flat matters.
Also, when you try to wax and you can't get the iron to melt wax on the middle of the base at the same time as where it meets the edge, it's probably time for a grind.