Designing a successful video game console is hard - just ask the teams that created the Philips CD-i, the Nokia N-Gage or the Atari... Anything After The Mid-80s.
Most systems go through a ton of revisions before anybody in the public gets to see them. These changes can run the gamut from minor to major - the Xbox One team probably went through a thousand focus groups before settling on a shade of red for the B button, while somewhere out there is a designer whose resumé includes "reduced the number of hands required to hold an N64 controller from five to three."
But there are some consoles that went through changes during development so significant, they didn't just affect that product, but the video game industry as a whole.
Sometimes it's a groundbreaking feature that was cut at the last minute, teasing us with endless "what if?" scenarios, others a serendipitous change forced onto the developers by circumstances beyond their control, or it's a company making a desperate choice that paid off in unpredicted ways.
And sometimes, it's just video game companies making really stupid decisions...