I must disagree. There is a strong possibility that the voting public and their representatives simply do not care.
Who really wants to help out a criminal?
I think it is wrong to deny a "rehabilitated" person their right to vote, 2nd Amendment rights, etc. If the person is still considered dangerous enough to warrant a restriction on their Constitutional rights, why are they not in prison? If a person has been rehabilitated, why does the government continue to deny them the rights enjoyed by all other citizens?
I have to agree with raimius on this. Not caring is the key.
Why is the drinking age 21 and not 18 when at 18 you can be sent to die in a war and vote? Because there are not enough 18-20 year olds who can get it changed and the 21+ don't really care what is done "to someone else".
Bring it closer to home for many here, why was it relatively easy to get an Assault Weapons Ban passed along with laws against concealed carrying of weapons in all but ONE state (VT)? Because there were far more people who simply did not care and allowed the process to roll on than there were to stop it. If it wasn't for the Sunset Clause most of this nation would still be stuck with it. In NY we still are as there is no sunset clause. You are not going to convince most people to actually rise up and oppose something that they have nothing to do with and in places like NY the vast majority of people could care less about owning an "Assault Weapon."
That is the whole problem here with laws banning felons from voting. Since most people are NOT felons they could care less about what is done to them. The general American gives nice lip service to the principals this nation was founded on but generally cannot tell you the difference between the COTUS and the DoI or even the names of three branches of gov't. They are that complacent, they are that ignorant.
Those representatives put into office can pass legislation further restricting felons with no concern whatsoever about loosing their votes or troubling the majority of voters out there to do a thing against it. Most people could care less about felons and the felons targeted by such legislation cannot band together their votes to support a candidate who opposes such actions because... THEY CAN'T VOTE. Unless the courts address the issue (which they may or may not be able to do, I am not certain) they are subject to laws passed and enforced with their own tax dollars to which they have absolutely no say.
Locking one group out of the electoral process while at the same time binding them to support it is against the very principal the revolution was fought over "No Taxation Without Representation." Having representation might not fix all your problems but NOT having it enslaves you.