Demi-glace acquired a bad image when Escoffier-style cooking was replaced by nouvelle cuisine. In the hands of poor cooks it had become a byword for all the flour-heavy, all-purpose brown sauces used to coat chops and steaks. The word jus replaced it, implying that no flour is used. Really gelatinous veal bones may be able to thicken stock sufficiently with no flour at all, but in my experience two or three tablespoons of flour, cooked out thoroughly in the liquid, will help the texture quite a bit.
Veal stock and demi-glace are time consuming and not worth making in small quantities. Demi-glace is made over three days, although there is very little work involved, and the stock requires occasional rather than constant attention as it reduces.