The word 'soft' in soft shutter release is a misnomer. It does nothing to change the resistance or travel distance of the camera's release button. I use one on the Nikon F2 because 1) it raises the level of the release button to a more comfortable position, 2) makes it easier to locate 'by feel' and 3) there isn't a protective collar around the soft release button (vs. the camera's release button) so there isn't any inadvertent pressing on something that won't trigger the shutter. With the index finger resting on the soft release, the finger is also in contact with the shutter spd dial, making it a snap to go from one to the other without having to hunt.
I use them on my Nikon F's for the same reason. Especially with an FTN head - it raises the button making it easier and steadier to press. The one on my Yashica GSN is just comfortable due to the larger area.
Moma don't take my Kodachrome away!
Oops, Kodak just did!