I think the issue is that we're so used to thinking of spacial dimensions, rather than the base concept of a dimension. Technically speaking any given texture could very well be thought of as an 8 dimensional structure rather than a 2 dimensional one you have 2 spacial dimensions(U and V) and 4 color dimensions, RGBA, and…
1d textures can be used to store more complex calculations. Although this is less true today with powerful hardware. But think about any mathematical function that takes a single scalar value as input. Of course the result (unless float textures used) wouldnt be as precise, but especially in older card generations it was…