Because GPL is hard to work with. I want to write code, not dig through legalese or discuss with a lawyer whether it's okay for me to do X or Y. More often the easier option is either to completely isolate GPL'ed bits (i.e. run GPL software on a separate machine so that there's no possible interpretation under which we're modifying it), or use something with a different license.
Or are you saying companies should be more willing to GPL their products? That's unlikely to happen.
Or are you saying companies should be more willing to GPL their products? That's unlikely to happen.