The old "if you've got nothing to hide, you have nothing to worry about" has always been a bull***t argument. Constitutional rights shouldn't rest on whether you've got something or nothing to hide. Try telling that to someone who's just had their house torn apart by state agents and all their financial records, computers, etc. carted away.
The main point here is that if the state can hide the underlying reasons for getting a warrant in the first place, the standard of probable cause can very easily be diluted to "a cop's suspicion or hunch". Not that this doesn't already happen quite frequently, but if warrants and their supporting material are kept secret, it makes accountability harder and misapplication for warrants much easier.
As others have said above, if police can convince the judge that a warrant should be sealed to protect a sensitive on-going investigation, as is the current law, that may be appropriate, but an automatic, blanket extension of this to all warrants is indeed a large step toward a police state.
The Patriot Act allows federal agents, upon application to and approval by the judge, to not even inform you if your house, car, business is searched (for 6 months, which can be renewed every 6 months indefinitely). They don't have to tell you what they take or copy, or that they've been there at all. It's all to fight terror...and then drug dealers...and then it may be too time-consuming to get the judge's approval, so let's just make all warrants no-notice warrants, since it will allow law enforcement to act quickly to stop terrorists....then drug dealers...then gun owners...then people who post on conservative web sites....
It is indeed a slippery slope. But then, you've got nothing to hide...do you?
Cheers.