I think you primarily need a better, more satisfying definition of "What is residuum?" before you can adequately tackle the larger issues to the point where you're basing a whole setting around it. Saying that it's raw magical material is insufficient in terms of describing its origin, scarcity, accessibility, renewable or expendable nature, cost, and so on, if you're basing a whole setting around it.
I'd also possibly consider amending your concept so that residuum is used to make durable goods, leaving things like candles and parchment to be made in the usual way. This creates a somewhat more diverse economy while still leaving everything dependent on this magic-based technology. It just seems odd to me that you'd have this material that you can use to make +6 Vorpal Broadswords and you're using it to make soap. Why not just make soap in the usual way, leaving more of the special material to make special things?
It would seem a bit weird to be using up the material that can make amazing magical items on something you use to blow your nose or wipe your ass. If Joe the Peasant (pause for horrific election season recollections) uses stuff made of raw magical material to pick the wax out of his ears or the gruel from between his teeth, what have you done to the wonder of this magical material in this setting?
If that is the effect you're going for, the sociological effects might be that nothing is considered sacred or special. Using another analogy, if you were to throw out the good china after using it once the same way you would your paper plates, it kind of loses it's "good" aspect, doesn't it? You could wind up with a very jaded, cynical society where the most amazing things in other campaign worlds elicit yawns. The very thing that allows for displays of wealth is now moot (that some things are made of special materials.) If the King of Wachovia has golden bedpans as a sign of his power and excess, but everything is made of the same material, why wouldn't everyone want golden bedpans? Just ask the ritualist to make them gold? Things like fashion and specialty items, and luxuries, are suddenly not so out of reach for virtually anyone. The result is that everything looks rich, but nothing truly is. Diamonds and gold attract attention because they are shiny and rare. But if the whole world was shiny, as most people would want it initially if they had the choice, then the whole world loses its luster.
Another question then that remains is, if you have everything durable made of a magical substance, and made via rituals, why wouldn't you make everything durable have magical properties? It's a bit like the old joke about the plastic doll being the only thing that survives a plane crash intact (why not make everything on the plane like the doll?) If the same stuff you use to make a spoon can be used to make a Spoon of Wonders! which allows you to flavor and heat anything you stick it in, and magical material scarcity is not an issue, why is every spoon not a Spoon of Wonders! ?
I think that perhaps there is an interesting idea here, but that using it for all goods or even just non-durable goods goes a bit too far.