Your fancy formatting and bullets don't change the fact that your thinking is critically flawed. The black market activity which you described does not reduce the amount of consoles sold in the long term. Microsoft is betting that the black market activity will actually create hype to increase the demand for the systems in the long run, which contradicts what you argued.
Don't believe me? Lets assume that the market for xbox 360s is willing to purchase 450,000 systems as you previously stated. If the shortage of 300,000 systems is produced then the market is still demanding the extra 150,000 systems. Microsoft does not lose out on the profits, they just cannot recieve them until more xboxes are released. Your flaw is in the middlemen. It doesn't matter how many people profit or are invovled with the process between the supplier and the consumer. Even the might Ebay cannot change the number of units supplied, and the number of units that the consumers demand.
Microsoft had two choices with the amount of systems to release. The first choice was to release as many as they could produce. Everybody who would want a system would get one, they would sell games, and then nobody would be talking about the system anymore. The second choice was the shortage option. I will stick with your numbers so with this choice 150,000 people did not get a system. They still want the system, and Microsoft is willing to bet that these people will be talking about it, and the added spotlight in the media will increase the demand.