I wasn't in the room when Hasbro made that decision (to replace Black Widow with Captain America), but my guess is that the demographic study was made that illustrates that young boys (pre-pubescent) are the primary buyers and that specific demographic prefers to play with Captain America in those particular toys over…

Just more Expanded Universe fluff.

The article was useless without any type of tangible description regarding what the hell he's talking about. It's akin to describing Quantum Mechanics without any description at all beyond "It'll be cool, man!"