However, I wonder if registration might have a positive effect on cyclists' behaviour too, the obverse side of your point 2 seems to be that not insuring/registering a car does appear to have an effect on people's driving:
'These uninsured drivers are 10 times more likely to have been convicted of drink driving, and are five times more likely to have been involved in road collisions, to fail to comply with other road traffic requirements and to be engaged in other criminal activity.'
The only reason that the majority (and thankfully that is a relatively small percentage of the overall driver population) of uninsured/unlicensed drivers are unlicensed is because they were bad drivers in the first place - measures to modify their behavior were simply not effective on the first, second, n+1 time.
Does the driving test really teach people to drive safely or is it just a chore to be done to get a licence - people need to know that if they drive badly in an unsafe manner that there will be consequences - an outcome that will only come about if there is a properly funded effective traffic police and effective sanctions in the courts - It should not be like that but unless what may seem to be harsh measures are taken peoples behavior will not change for the better.