I use these in my Gator cymbal hard cases. As far as I can see, the protection that these things offer is from scratches caused by the cymbals being in direct contact in the hard case. Of course, the hard case itself is what protects them from any impacts.
I don't know how much protection these actually offer and how much of it is simply peace of mind provided by the fact that when you pack your cymbals away you don't hear the metal-metal contact.
You could DIY these using slightly thicker, spongier neoprene from eBay, for example.
