In isolation, it may be argued that DNA retention would be useful to the Police in their work. However, put it against the background of everything else going on in the UK, and it becomes impossible to ignore the more sinister overtones of dictatorship.
It is very easy to formulate an argument for single items, for things that only affect a very small proportion of the population, which is how the salami slicing works.
However, when we put it all together, 26,000 new laws, 3000 new criminal offences, then the laws are not for the good of the people, or for their protection but for the good of the state.
That is the balance that needs to be redressed.