Is this multiple signature feature for m of n or is it rather for 2 of 2. What I saw in the code was rather a 2 of 2 kind of scheme - and I did nto check if it is really turned on or just in the code but disabled.
See here: https://en.bitcoin.it/wiki/Contracts (CHECKMULTISIGVERIFY)
Getting the coins to a new address with keys is certainly possible and fun for the freak, for the John Doe user it is a no-go. Just compare: This new fine leather wallet is secure. You just have to move your coins into a different one every other day!
Agreed, just have to make sure that key renewal really is a lot more convenient.
Imagine you lose the secure device. Or drop it. Or your cat pees on it. Your son runs his bike over it. There goes the access to all your bitcoins. 
The secure device holds no data, it's just used to generate keys and write them to the usb drives/smarcards/whatever. It's also used to sign transactions based on the keys on the usb drives/smartcards. If it gets lost, stolen or broken, you just get a new one.