Memory is also used to store your data, so if you are the type that likes to load productivity apps, utilities, and games on your desktop, you're likely to need more memory on your handheld as well. That said, if you need a handheld just to organize your contacts, even 1MB Palm-size devices may suffice.
Extra memory adds to the overall power consumption of the device.
Memory for handhelds is also more expensive than memory for desktops and notebooks. Delivering the latest shopping news to your in-box.