Yeah, if I were looking for high accuracy I wouldn't use this type, currently not that accurate.
Where I can see uses for this technology would be for something like an attachment for indexing a lathe headstock that could also at as a tachometer. Since all it needs is a small radially magnetized magnet glued or attached directly, I can see using it for initial setting of a cross slide angle and possibly for positioning a mill head for angle cutting and get it close before tramming.
From what I've gathered, this is the technology the automotive industry is using for cam and crank position sensing, steering wheel position sensing, and even wheel monitoring.