The simple, cynical explanation is this: if you create a multitude of unenforceable (and largely unknown) laws, then virtually EVERYONE becomes a criminal, consciously or unconsciously. And, since enforcement is spotty at best (or worst) there is widespread, perhaps unintentional, non-compliance. Everyone, therefore, becomes a criminal, and it is up to the state to pick and choose which of its enemies it wishes to incarcerate.
It no longer becomes necessary for those in power to trump up charges against their political opponents, since the laws are already on the books. Because of this, the Constitutional protection against unreasonable search and seizure is the most important part of the Bill of Rights; it is the only thing standing between the average citizen and prison time. If, for example, the Polizei were permitted to just ransack your residence in search of nothing in particular, it is almost certain that they would find something that would justify legal action.
Exactly. If your a fan of Terry Pratchett's discworld series Samuel Vimes the Ankh Morpork city watch commander( not that they do much Lord Vetinari is pretty libertarian except if you try to overthrow him and then he has this thing about mimes...) observes that it might be possible to go for a day without breaking any laws by remaining very still in a cellar somewhere...but even then you were probably loitering.
Which btw brings to mind another fault of Republics( actually this flaw would apply less to a pure mob rule Democracy). Since the legislatures job is making laws they tend to multiply endlessly.