Certainly not a terrible idea, I like it. Though we should have more things than just annual voter registration to deal with inactive people. Perhaps depending on what proposal(s) we start to draft we can implement things such as, for instance, if we implement a parliamentary system that involved a lower house comprised of all the citizens, we could strike those from the rolls if they don't vote in a certain number of consecutive legislative sessions.
An excellent idea.
It reminds me a little of an argument used over here in relation to compulsory voting. As most would know, there is compulsory participation in Australian elections. One of the arguments in favour of compulsory voting is that voting is a right, true, but it is also a responsibility - that rights and responsibilities are two sides of the same coin.
If we provide everyone the opportunity to participate - such as through a universal model, then people have the right to participate but there should be a minimum participation requirement to ensure that people fulfil their responsibility to participate also. If someone is not prepared to carry out their duty/responsibility to take part, then there's a good argument for removing their ability to participate in elections.