Correct me if I'm wrong, but you should be able to loopback-mount a "proper" file system (e.g. ext4) from a file on NTFS, and then you'll have no limits other than what ext4 imposes. Of course, you then lose easy interop with the filesystem from Windows side, but that is the inherent trade-off here.
WSL doesn't actually run a Linux kernel; it emulates the syscalls and process environment Linux offers and provides a binary loader. It's WINE in reverse.
So there's no ext4 driver, and no concept of loopback mounts.
Ah, indeed (although it's not quite WINE in reverse, since WINE emulates userspace calls, not kernel syscalls).
I see that there's considerable demand for this exact thing in their bug tracker already. If they go for a low-hanging fruit here, it'd be FUSE support - and that should give us ext2, at least.
