I feel that it is unhealthy that the majority of organisations (appear to) have such clauses yet at same time often they wouldn't be in existence if it were not for the OSS they build their products and services on.
I built this policy for my org and blogged about it here http://dhickey.ie/2014/11/our-open-source-policy-at-evision/ . I feel is strikes a balance between the business concerns and contributing to a healthy ecosystem. I would like to see more organizations take a similar approach; your feedback appreciated :)