Surely, /surely/ this is the least of their concerns. Since when did we get so sloppy as to assume byte ordering in files? When was the last time your PNG loader failed on x86 because the file has big-endian fields?
In the console programming world, cycles are precious. You don't tend to waste time doing things 'just in case', you're much more likely to assume a best-case scenario and engineer things that way.
In terms of endianness, it's not a huge problem - the toolchain normally copes with this, as assets are built individually for each target platform. This is what we did last time I worked on a cross-platform game anyway.
