I think the threshold would be, did Linode take "reasonable" precautions in protecting the servers in question. Just like the landlord or bank. So long as they take reasonable precautions, they can't be held liable.
You can expect for your landlord to keep their copy of the key in some sort of lockbox, but you aren't going to expect them to keep it in a pressure-sensitive safe, guarded by movie-style lasers and a German Shepard.
You expect a little more security out of your bank.
The real question is: why were services that act like bitcoin banks storing their coins on Linode in the first place.
Reasonable is subjective, I believe all hosts should use an NIDS and a HIDS if they don't I in my opinion consider them amateur. Regarding resource utilization sampling connections periodically would not take much.
The only (realistic) way to generate bitcoins today is with GPU or other specialized hardware that doesn't exist on webservers.
These servers that were compromised were used to manage generated bitcoins. One was used by a pooled mining service (mined coins were sent to the server then payed out to miners) and the other was a faucet service which would give a little bit of bitcoins to new users. The other 6 servers that were compromised are unknown to me.
You can expect for your landlord to keep their copy of the key in some sort of lockbox, but you aren't going to expect them to keep it in a pressure-sensitive safe, guarded by movie-style lasers and a German Shepard.
You expect a little more security out of your bank.
The real question is: why were services that act like bitcoin banks storing their coins on Linode in the first place.