I agree with all that's been said. My machine dealer likes to remind us frequently that 'you paid for all those stitches, its a good idea to try them and use them.'
I do use them for quilting through all layers. Recently through the top and batting on part of the wall hanging with the more closed and complex stitches and then more simple ones through all layers for the rest to complete the quilting part.
I also have sample strips of the decorative stitches - it really inspires you to use them more often and they are so much more appealing than the line drawing you see on the stitch guide.