Standard data cleaning metrics show that data in any contacts database degenerates at a rate of around 30% a year, just through people moving, changing jobs, getting new phones - all the trivial things we never really think of. It's a massive problem, and the companies set up just to help people clean corporate contact databases struggle to keep up with things.
Now imaging trying to keep the data of everyone in the UK clean. It's going to be virtually impossible. And the national database will be storing much more than just where everyone lives.
So, you have to ask yourself, are you able trust a national ID database?