I very intentionally didn't mention the browser as an application you'd want to be 32-bit. I thought about Chrome's model of one-process-per-tab, and decided I still liked the larger address for mmap and IPC purposes. The browser (or, at least, most of it) should be 64-bit. Perhaps there'd be sufficiently low overhead to have just the JS engine 32-bit.
Your browser is only one out of hundreds (if not thousands) of programs on your computer. Many (most?) of them only run for a few moments, or otherwise don't (or don't derive meaningful benefit from) consume huge amounts of memory memory.
Take the 'dd' command. top. ls. bash. dash. cp. mv. echo. cat. tee. cupsd. dbus-daemon. lpr. grep. find. xargs.
The programs you spend hours every day staring at? Yeah, those probably benefit from having a 64-bit address space. The programs you don't think about, often when you're not even actively using them? They probably don't.