The usual fear is that the government itself will use this information (or, in this age of
contractors, get someone else to use it on their behalf) and that since the government is
capable of being incompetent and malicious (more the former than the latter but don't rule out
either) this is not desirable.
Personally I think it may well be undesirable but it's inevitable and instead of trying to
protest it we should try to create safeguards that make it harder for government to abuse this
information, easier for both elected and unelected officials to be held responsible when it is
abused, and easier for us as citizens to know what's actually going on.
Open Government and Freedom of Information are better for us here than the Data Protection
Act. It's unrealistic to expect an organisation which specifically hires /spies/ to stop
spying on us. But we can ensure that they can't abuse these powers with impunity. When we have
a Home Secretary arrested for authorising illegal snooping then we're equal again.