It would make memory-poor phones more viable. Like why can't we have a 512MB, or even 256MB RAM phone. Although I doubt that the software effort would be cheaper than just buying the extra RAM. It's definitely much more uncertain.
https://wiki.openmoko.org/wiki/Neo_Freerunner https://wiki.openmoko.org/wiki/Applications https://wiki.openmoko.org/wiki/QtMoko
Before that Linux ran on the Zaurus too:
https://en.wikipedia.org/wiki/Sharp_Zaurus https://en.wikipedia.org/wiki/OpenZaurus