From a purely moral standpoint, I think refusing to pay inactive addresses is wrong. It's due payment for past work, it shouldn't be pushed back indefinitely.
No, this is dealing with Extra Credit (EC), not unpaid rewards.
It also punishes the creation of new addresses, which beats one of the selling points of mining here ("virgin coins"). There is already a "new address tax", there shouldn't be any more.
There is no "new address tax" right now... if there was, it wouldn't be a major downside to this proposal.