Дык игры больше места занимали, чем у других приставок

И собрать картридж вообще как-то дороже, чем отлить кучу дисков.
Ну и нашёл тут
телегу про монополизмъ. Судя по первому комментарию, разработчик от цены картриджа ~10% получал, остальное шло нинтенде - роялти, затраты на производство и т.д.
Nintendo set minimum production amounts, normally 15,000 copies at minimum. You get to choose who does the packaging of the carts.
Production costs: First you have the production costs. Nintendo makes the carts in Japan at their factory, so they get the money from production.
Then nintendo takes a royalty, say $7 each cart for logos, nintendo seal of approval, etc.
Packaging runs you about $150,000 for the 15,000 carts. This includes manuals, the boxes, and shrink wrapping. This does not include delivery fees.
In the end on a $55 cartridge, a profit of $6-7 was made by the developer. Nintendo got all the rest. This is why nintendo didn't abandon cartridges for CDS. They were addicted to the money.