no freaking cell phone or tablet needs 64 memory addressing (which all 64 bit does, grab twice as much memory at each cycle, the CPU has added memory registers THATS IT). Don't be fooled by the hype. If you device needs over 4GB of ram it's due to bad programing and bad memory management on the kernels end...not the hardwares fault.
64-big processors have far more advantage than being able to address more than 4GB of RAM. This is a common misconception (and also, it sounds like your understanding of 64-bit systems is not correct).