As others have mentioned 'Smart Motorways' actually covers 3 main types:
The Variable Speed Limit only, as we've had for many years, is fantastic and when used effectively (and obeyed) can keep traffic flowing very smoothly.
Dynamic Hard Shoulder (i.e. only open when required) is good, although the junction designs can be rather ineffective as the hard shoulder turns into a full-time running lane then back into a hard shoulder, but there's no indication between a short stretch for merging or if it's a genuine lane gain, which leads to wasted capacity. However, because of the regular confirmation of the status of the Hard Shoulder, and the fact it's only opened if the motorway is very busy and the speed limit reduced, it's generally used properly.
All Lane Running is the most-criticised aspect of it. I personally don't like it - Motorways are meant to be critical infrastructure, and the loss of the emergency facility means recovery time will likely be longer. However, it's not intrinsically unsafe. By far the biggest problem is that most drivers seem to think lane 1 is still a hard shoulder, and so don't move left (and don't get me started on drivers who sit in the 2nd lane from the right at all times), which makes the widening effort pointless and leads me to question how many schemes should be binned in favour of just making sure drivers keep left, leave a safe distance, and actually make overtaking moves rather than very gradually drive alongside for 5 miles.
Making the theory test only valid for 5 or even 10 years would be relatively straightforward to do. Give drivers a window in which they must pass the test, even if they fail their first attempt they don't lose their license so long as they pass another attempt later on within the 6- or 12-month window. If you pass earlier, you still keep the original anniversary date so you wouldn't have drivers deliberately leaving it late to try and preserve their validity. This would probably only have a minor effect, but often it's small things on the big roads that set up situations where accidents occur (e.g. Following too close, not making good progress in the right-most lane)