The Falcon game was not his fault, he had one blocked and one botched snap. The Colt game he had one miss he should have made and one really long kick. He was near automatic all year and it would be a big loss if we lost him.
Before the playoffs Shane and Nate were top-5 kickers. You'd rather have them over Feely? If we released Feely he'd immediately become the best available free agent kicker. That alone says we should retain him.
It's not a good sign when other Kickers around the league miss clutch FG's, and the commentators say, "He 'Folked' that one..."
You're probably right, I've just never been keen on the idea of using the franchise tag on a kicker, even if it has been done before. But with the uncapped year and 2 franchise tags at the team's disposal, maybe it's the most viable option.
The Cardinals signed him when Rackers got hurt. And they cut him when he got better. So Nugent could get signed with no final 4 rules or anything attached.