because heavy, prolonged rain is actually quite rare
IME you only need one or the other to defeat a soft shell, rather than both together.
And while I'd agree it's the case that one doesn't really need a hard shell that often, it only takes one really bad session to render a bad day utterly, utterly miserable. And if that involves spindrift and gales together then the difference between a cheap, light shell and a more expensive one with a serious mountain hood is worth paying for, both in money and weight. This becomes more the case with colder temperatures and longer days: a summer dander and if I get wet, well so be it, but a long winter walk with a few tops and maybe an overnight I'll want a good hard shell as a priority item.
spend your money on the softshell or softshells that you will be wearing most of the time?
TBH most of the time I just wear a base layer and if it's cold a midlayer too, finding that something like a Paramo reversible shirt is windproof enough that as long as I'm working I'll be quite happy without bothering with formal windproofing. Again, the want of something more serious goes up as the temperature and daylight go down, but most of my ticks have been without either hard or soft shells on.
Pete.