I'm sure there are programs out there that write data structures as-is to file then read them back in some time later in the same process, perhaps in a low-memory environment. I can also see it used for low-level programming where the program is loaded at the same address every time. It seems like a bit of an arbitrary restriction. When reading in `void[]` - such as with std.file.read - an explicit cast is needed to interpret the data in any meaningful way; I think that's enough of a restriction.

Anyway, it's not important to me, and the restriction can always be lifted later if someone needs it...