I think we're talking about exactly the same thing :). That's what I meant by "even they rely on being stored in a physically secure room and protected from theft". Despite all the hardening that is applied to the device, it must always be kept secure and supervised. As an example, this is what Safenet considers the intended installation environment should be [0].
This can't be effectively applied to a personal computer.
[0] http://cloudhsm-safenet-docs-5.3.s3-website-us-east-1.amazon...
Then your biggest problem is people thinking that stealing the cards will get them anything. Which, they're not entirely wrong, because those things are damned expensive. So you need a 'kinda' secure facility.
Again, the issue is that any hardware that will start up for you without any action on your part will likely start up for anybody else, too. Your laziness will probably win out...
Not exactly. You don't want someone sneaking in and misappropriating the HSM to authorize something bad. And if you set the system up for unattended recovery from a power failure, then in all likelihood someone walking off with the server the HSM is in can use those keys indefinitely. But there are options.
Some HSMs have self-destruct mechanisms that attempt to prevent physical access to the private key (ie by lapping the chip). Some vendors (nCipher, IIRC) have a smart card (a second HSM) that is required to authorize certain activities, like signing, or key recovery. In fact they had a byzantine generals solution that either had the key or a password for the key split between n cards. In the latter case you needed one of the original HSMs in order to clone the key, so a movie plot where you kidnap the entire team at a conference doesn't work. During initial setup the cert would be generated on the first HSM and copied to the others, having never seen daylight.
That system was quite difficult to explain to users, and I had to document it just so I wouldn't get confused and trigger a reset of the evaluation hardware (at which point all of our test artifacts have to be rebuilt).
It might be more complicated to start WWIII than to protect a signing certificate, but only just.