Personally I don't see a lot of use for that, since textures can be swizzled into hardware tiling modes offline and just loaded directly into memory that way. There aren't a lot of algorithms on textures that call for linear CPU access, and most that do have GPU friendly versions anyway.But...
If the data is in a layout which is sub-optimal for either the CPU or the GPU it will be more optimal to use a move engine to swizzle the data, carry out other work on both to hide the latency then complete the processing you wanted to do on the data.
This makes the Xbox harder to program for in general but gives a good amount of scope for optimization.
Unless this is more macro swizzling like copying from an interleaved buffer out to separate linear buffers (for better coalescing) or vice versa. That sounds like it could be useful.