From how they state it, the 'high risk failure' part is only for the special double slotting of Materia into equipment, and is likely naturally not something you do all the time, but only try for when you have the best chance possible, and on gear you really want to keep.
Beyond that, the normal, everyday slotting of Materia was stated to have no failure chance whatsoever.
And besides, nothing says that you 'must' spend your days grinding out the creation of Materia. They seem to develop throughout your normal play experiences, and from there it would be no more difficult to get the Materia crafted into an item then it currently is to get an item crafted.