I'm just wondering what is the tenacity of hardware wallets in terms of long term use. Even flash drives have a limited time. It would be scary if one day your trezor have some "hardware error" 
The crucial point is that you can use a hardware wallet for every day usage. It is pretty handy in accessing your coins and making transactions without
exposing your private keys. You can still sign transactions on an infected pc without your coins getting lost.
Standard flash drives can be written up to 1.000.000 times. Even if your usage exceeds this limit its still possible to just easily recover your coins from the
12/18/24 word seed phrase. And if you are performing this restoration also on a hardware wallet, your priv keys aren't exposed to theft anytime.
And this without any technical knowledge. So IMO hardware wallets do have quite some additional value.