You sound salty that GBC sucked outside of just a few games and everyone wanted a Neo Geo Pocket or Wonderswan instead.
Yeah, "everyone" wanted those systems.
How much did they sell, again?
The entire idea for the Game Boy line was to use way suckier hardware than the competition, and it worked. (The spirit of Gunpei lives on in the Wii and Wii U I guess.
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In 1996-1997 or so, game boy sales were tanking, especially after the death of the Virtua Boy. So Nintendo started up on Project Atlantis. Developers were starting to say they refuse to support the game boy due to its limited 1989 tech, that it was outdated, and they couldn't make the games they wanted to on it anymore. Meanwhile, Wonderswan and Neo Geo Pocket started to take off and yet Nintendo still needed a band-aid to help the developer situation for the GB to prevent developers jumping ship. GBC was their temporary answer to the much delayed Atlantis. GBC was a rushed band-aid solution because Atlantis wasn't complete and they still needed a successor. Its tech was marginally better than the GB's, and many developers didn't deliver desired results. Most of the best gbc games weren't heavily advertised, and bombed. The best sold ones were the ones made by Nintendo, because they were heavily advertised, giving the idea to the public that the only good gbc games were Nintendo games - which was false.
Eventually, Wonderswan and Neo Geo Pocket added color when Game Boy Color did, and they got lots of attention. Not Game Gear attention, but in Japan Wonderswan took out 8% of Nintendo's portable market in a very short time. Many of the big boys started to get big support on the Wonderswan, especially Squaresoft and Namco. Eventually, Nintendo needed a response and released the GBA very neat and quickly. GBA was a rushed product to combat the competition, much like with its predecessor the GBC. That's why the quality on it was so bad upon release. The GBA killed any support the competition even remotely had. It's easy to say in the present that they had no threat towards Nintendo's bottom line, but GBC and GBA were definitely direct answers to them and forced Nintendo's hand.
Your summary of GBC sounds like pr speak, no offense.
The history of Game Boy is a great example of Nintendo's conservatism. They had the same tech for practically (I say practically because GBC isn't much of a step up from GB) 12 years and when they did release their next portable, it was almost impossible to play on due to measure cutting (no backlight in 2001

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In fact, I'd go as far as saying that the Game Boy is where Nintendo realized that they could come up with the same stuff and people would buy it. After the failure of the Virtua Boy, they hammed it up and released the GBC.. With GBC, Nintendo probably realized that people will buy their hardware even if it's not much of an upgrade, and told them that people are more than willing to pay for rehashes. ZELDA LINK'S AWAKENING!! THIS TIME...IN COLOR! And so on.