Out of all the cartridges for all of the game systems ever created, I'm the most fond of the line of carts for the Famicom system. The reasons are actually pretty apparent:
- They came in all sorts of colors.
- Different developers ended up making different cart designs. It's like Bandai carts had a different shape than the standard Nintendo cart.
- This was the first real game system I remember from my childhood.
Nintendo did attempt to do some variety in their cartridges for future systems down the line, but they were pretty limited in terms of quantity. The Pokemon games had their own cart colors as well as some special edition Nintendo first party games like Zelda or Donkey Kong. Outside of that, however, you never saw a red cartridge for the new Punch-Out game or a black cartridge for the Shadowrun SNES game.
I'd really like to collect these for the sake of the carts and their design.
Famicomblog has a good post about this too.