I have the same sentiments with you. There would be no bonus abuse if and only if the casino is conducting a maintenance, daily checking, or update on their security measures and servers. If the casino's security is strong enough, no one will be able to bypass and exploit the system. But if the security is weak and they are only conducting checking complacently, then certainly there would be bugs and glitches that would occur.
And as we know, the moment people know that there is a vulnerability in the system, they will utilize and take advantage of it for their own benefit. There are only a very few who will be honest and kind-hearted to report the glitch in which they can profit from. While both may be at fault because taking advantage of something that is just an error is bad, the casino is in greater responsibility of bonus abuse.
I cannot agree with this, anyone that knows anything about computers knows that it is almost impossible to create a system that is bug free, so even casinos that are doing their best are going to present an error or two once in a while.
Also most casinos on their terms of service directly state that if there is an instance in which a bug is found by their clients they have to report it and to not abuse it, so by playing at that casino you have made the compromise of not abusing any vulnerability, so in that case is my opinion the player is completely to blame if they do something like that.