The .NET shell does this, but that's why it's not Unix, and it's not universal.

If programs passed data structures then either you're forcing a certain data structure model (i.e. it's not universal, because it's not compatible with anything else), or your data structures are so general (i.e. a block stream) that your applications are going to be parsing anyway... and that's going to be even nastier than if everything was stupid text steams in the first place.