I think much of the bloat or bloated appearance of OS X comes from its Unix background. Rather than wrapping everything in a single file, things like applications usually come in thousands of files once they are localised and contain help. You can see an (over-dramatised) effect of this if you time how long it takes to copy your iTunes application: much longer than copying that amount of data should take. It may sound like a heresy, but the good old resource fork was a way around that kind of problem ;)

In any case, if it at some point turns out that Earth was seeded from elsewhere (which is far from certain based on the current evidence), this would be the science story of the century. Perhaps the building blocks of life arise spontaneously all over the galaxy.