You're just going to go down to the ground with this, aren't you? If a cable (or adapter) that's mini-DP to DP comes along in 2 months, will you still say it's such a terrible mistake? How many monitors have only DP input? (Apple already makes adapters that go from mini-DP to DVI, mini-DP to dual-link DVI, and mini-DP to VGA).
You seem to want to win an argument rather than look at the real possibilities (and probabilities).