That's because the storage provides a measurable benefit to the buyer. "Hey, I can 16GB for a subsidized $200, but if I spend 50% more money, I get 100% more s

That's because the storage provides a measurable benefit to the buyer. "Hey, I can 16GB for a subsidized $200, but if I spend 50% more money, I get 100% more storage". Every computer manufacturer does this for both RAM and storage. Mostly because the take-rate for memory and storage upgrades are far higher than, say, CPU upgrades which provide less measurable benefit for a significantly higher cost to the OEM/system integrator.