As much as it pains me I see two sides of this issue:
1) Anyone who is a public employee is subject to oversight in my humble opinion. Especially folks that wear badges, carry weapons and have arrest powers. It effects several of the rights of US citizens.
2) I understand the need for operational security, especially where organized crime (drug cartels, for example) are involved. If SWAT is used, for instance, in taking down a major drug dealers "safe house" and the probable cause they had was the result of undercover police then I'd say that is an example of records that need to be sealed for the safety of the undercover police involved. Undercover cops hang their skins over the line enough just doing what they do.
There needs to be a fair balance between allowing law enforcement to do their jobs and the public "right to know." Some secrets I don't believe should be public knowledge if the safety of the lives acting on good faith are involved. Remember: law enforcement is done by human beings.
I shudder to think of a "Robocop" scenario playing out in this country.