I am tempted by quilting cottons everytime I go into my local fabric store - they have much better prints and colours than the dressmaking cottons. I do agree with the Colette post - they probably should only be used on garments that require a little extra body/stiffness, because they do take a long time to soften up completely - which is a shame (when wanting to use them for garments).
Maybe with the resurgence of garment making the choices of fabrics will increase - we can only but hope!
I love the texture of quilting cottons and I hope to use it this summer... My fabrics choices goes more with my fingers than my eyes recently as I made bad mistakes (mainly cause I liked the look of it) ...
Im sure they are a delight to sew as many wont require lining.
This is the philosophy I have too, in regards to use or not to use. Since I sew vintage patterns mostly (or vintage-styled), quliting cotton "hand" is suitable for a lot of my projects. Heartbreaker Fashion is a retro clothing company, and they use a lot of quilting cotton prints in their dresses, if you would like to see some structured styles that work well with these fabrics.
Mostly I think you shouldn't follow anyone's rules but your own. :)