Furthermore the bad stuff falls down on the launch site, a good deterrent to the rogue nation or agent. This politically incorrect solution seems to be the only solution to posed obstacles. Existing contractors don't like it because it is a new approach limiting their competitive advantage. The administration doesn't like it because it junks already moribund peace pacts. Your points are well taken.
Space is obviously the ideal place from which to provide global missile defenses.
The real impediment to doing so seems to me to be the ABM Treaty which explicitly prohibits, among other things, space-based defenses. It mystifies me that we are willing to pay the terribly high cost of waiting for that event before we take steps that might prevent it from occurring, first from the sea and then from space. The fundamental problem is that the satellites must orbit the Earth at relatively low altitudes, typically less than a thousand miles, in order to be relatively close to the target missiles. This means that at any given time, most of the space weapons would be orbiting over some part of the Earth other than the location from which hostile missiles might be launched. Since most of the space weapons would be absent from the front line, anywhere from ten to several dozen space weapons would have to be in orbit in order to have one properly positioned at all times.