I am not sure asking is the right thing, I think tmpfs in RAM should be an *optional* supporte dfeature for those users that have a workload that *will* benefit from this feature and therefore *will* seek it.
It could have been as easy as a checkbox in the disk partitioning screen of the install:
[ ] Use RAM and swap for temporary files
Perhaps checked/unchecked/disabled via some logic (enough ram? swap enabled? some /tmp listed in fstab?) but let the user decide.
I do occasionally run swapoff -a I do that when I *know* the system is trashing just because the kernel is caching a lot of crap and swapping out a working set that *do* fit completely in memory if it weren't for the stupidly overly aggressive buffer caches.
echo 1 > /proc/sys/vm/swappiness