[cdown]

> I never saw programs I would actually want to use try to allocate that much

What about applications that have memory-bound performance characteristics? In these cases, saving a bit of memory often directly translates into throughput, which translates into $$$.

This isn't a theoretical, a bunch of services which I've run in the past and currently literally make more money because of swap. By using memory more efficiently and monitoring memory pressure metrics instead of just "freeness" (which is not really measurable anyway), we allow more efficient use of the machine overall.