John Gruber praises the iPhone's lack of upgradeable storage:
I simply don’t understand why Motorola doesn’t follow Apple’s lead and provide ample built-in storage rather than relying on removable SD cards.
He overlooks an obvious benefit of having SD cards for storage: they're cheaper! Compare what it costs to equip a device with a substantial amount of memory:
iPhone 3G S Droid 16GB $199 $199 32GB $299 $279
Apple has a long history of gouging its customers on non-upgradeable memory. 32GB of data is the maximum amount that iPhone users may accumulate. Droid users who have >32GB of data can shuffle multiple cards.