sure go for it.
Welcome to the Quilting Board!
There is one disadvantage to a quilt finished with a seam on the outer edge. The edge gets the most wear and tear, so a bound quilt with two layers of fabric on the outer edge will hold up better for frequent use and washing. My quilt guild makes charity quilts that are expected to get lots of use and washing, and we finish them by cutting the batting and backing (after we tie them) about 2 inches bigger than the top. Then we turn then under twice to make a narrow frame on the top of the quilt and machine stitch the "binding" in place. If you are using a thick batting, you will probably want to cut it even with the top and just have two layers of the backing fabric on the outer edge.
Tying (we use perle cotton) and finishing a quilt this way is a good way to finish up some of those UFO's sitting in the closet. UFO? Unfinished Fabric Object. They tend to breed when left in the dark ; )
I was just at a quilt meeting this week where the speaker said you can do just that!!!! Go for it!