We could, but it would have broken compatibility with v4 just as thoroughly as v6 did and so would have had the exact same deployment difficulties v6 has. In f

We could, but it would have broken compatibility with v4 just as thoroughly as v6 did and so would have had the exact same deployment difficulties v6 has. In fact v6 mostly _is_ a minor tweak to v4; most parts of it are lifted directly from v4 but with a longer address.