I have a quite complicated but completely real use case of OffsetArrays, at least 0-indexed arrays. The problem I face is a research project for something related to Clifford Algebras.
Basically the researcher that I work with though, along with a PhD student, about a representation of Spinors based on a binary representation with a base over {\mathbb{C}^2}^{\lfloor n/2 \rfloor} that works remarkably well when working with operators of Clifford Algebras.
Given the binary representation, the basis of spinors of an n dimensional space is represented by the integer numbers in the range [0, 2^{\lfloor {n/2}\rfloor}-1], and the coefficients are just complex. So a spinor ends up being just an array with indexes beginning at zero, filled with complex numbers. The beauty of the base they choose is that in the most interesting cases for the work of the researcher, most of the coefficients ends up being zero. So you really only need to use sparse arrays.
You could of course use 1-based index and do all the calculations of the basis putting manually the offsets every time you are going to index, but it is a lot easier (and readable) to just have the indexes start at 0. The researcher is not by any means a programmer, but I promise him that he would be able to write code that would make sense, be fast and easy to understand for him. So I need to use and work with 0 indexed arrays. 