The blade is soft because it is sharp and requires less pressure on the skin. In my experience, the sharper the blade the softer it is and technique is more important than the razor.
Good point! I have hard beard growth and that is probably why it works best with a sharp blade.It all depends on your beard really. If you don't have a hard beard and a mild blade can do the job, there's no point in risking cuts with sharper blades. I use only the R41 and sharp blades such as BIC, Silver Star, ASCO and German Wilkies. Mild blades like Voskhod and Astra SP tug and there's no reason to use them. With even milder blades such as Sharks/Lord Cool, they are good blades and I can shave with them, but I have to work real hard and go over the same spots many times which increases irritation. For example, with Shark Platinum I had to stop after shaving one half of my face because my hair was being ripped off instead of cut.
But if I had a softer beard, I'd gladly use Shark SS over a BIC.