By the way, don't get me wrong...the rest of your post is reasonable and adds to this discussion.
Not trying to dis you...
Those potential impacts are crucial to me. And I believe such a tax would cripple the real estate markets which would be disaster.
Income taxes appear to be necessary to fight modern wars as well since I see no other mechanism to raise rapidly and effectively the hugh revenues they require. It is no accident that the first income taxes were imposed to fight wars: Britain against Napoleon and the US against the CSA.