> The biggest benefit is the ability to access more than 4GB of memory. For reference, the iPhone 5S has 1GB of memory.
No. The biggest benefit as having an addressable virtual address space which is in the tera/peta/exa byte range. Which makes a lot of things simple and efficient, even if you don't have a lot of physical memory. Read about e.g. LMDB's design or Varnish's design for good examples.
The other significant benefit is more registers.