There is a mountain of regulation, most created by delegated authority emanating from enabling primary legislation, and much of it with unforeseen ramifications.
This essential initiative of the Government presents a valuable opportunity to reassert some core libertarian principles, one of which is that there should be no requirement to inform the state that one is not committing an offence. Therein lies the philosophical principle, but there is also an important practical aspect (which I suspect would be borne out by a proper analysis of SORN statistics); the effect is to harm many of those for whom the provisions of SORN were never intended to apply. Couple that with the fact that the police already have access to databases telling them whether vehicles are taxed and insured and you reinforce the fact that the SORN is a pointless and redundant burden. As I said above, repeal it and you free up the police to go after those actually driving on the road without tax and insurance, whilst removing an unnecessary piece of bureaucratic red tape from those least able to understand it. It really is a win-win no-brainer.