From the Raspi perspective, the jump from 256 to 512 was too great, making a BIG difference to the price. 512 PoP ram is very expensive. As to other mem size, they are no not made in the larger sizes in the right PoP format. The CPU can address 1GB I think, maybe more.
In other products, it's also about cost. Why put more <whatever> you need in a device? It make the product cost more for no added benefit. You example, the product works fine on 64MB. Why put more in? Just makes the end user price more expensive, or makes your profit margin lower.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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