Personally I subscribe to the 'don't let the blighters get on the flight' school of thought.
This is a great idea, but, as with everything else in aviation, is better with several backups.
What need is there on an aircraft for auxiliary hydraulic systems, when the engineers could just design them not to fail in the first place?
Prevent engine fires by designing an engine that can't catch fire.
Prevent engine failures by designing engines that don't fail.
While stricter ground security is absolutely necessary, it cannot be relied on to keep the bad guys off passenger aircraft.
The maginot line worked great for our French brothers, didn't it?!