A softshell for running will be very lightweight and will not provide the same protection as a heavier version for walking and trekking. Hiking softshells are highly water resistant - that means they will shrug off a short shower without the need for a hardshell - this means on changeable days you can keep the same garment on all day and be comfortable - try that with a hardshell and condensation build up inside the garment will get you wet.
