It might be nice to look for baked goods that aren't meant to have icing, just for some variety. For instance, I have a recipe for pound cake that seriously would taste worse with icing than without it. It's really meant to be served entirely on its own (with maybe just a dusting of powdered sugar). I also make brownies that are so sinfully delicious, icing would actually detract from it.
The other thing is that icing recipes don't necessarily have to be followed exactly. I don't make icing all that often (because I don't bake all that often), but the ones I gravitate towards are the ones I can play with a little. Hershey's has a recipe for chocolate icing on the back of their Dutch Cocoa container that I really like -- it's cocoa powder, powdered sugar, butter, and milk. I use the proportions in the recipe largely as a starting point, and to get the butter and chocolate ratios correct. But once I've mixed the cocoa powder into the melted butter, I play the "add a little milk, add a little sugar, repeat" game until it's the right consistency with a flavor I like. It would be entirely possible to make a dark chocolate icing that wasn't very sweet -- you just wouldn't add as much sugar and milk. You'd end up with a little less icing that way, but you could always compensate by just increasing the recipe a little.
Glazes and other such icings can probably also be played with somewhat to reduce sugar content, as long as you can get the consistency the way it needs to be.
