If your systems are exposed to the Internet, then deploying security patches quickly is a part of keeping the systems running - as illustrated by this case, where the systems obviously are not running and can't be easily rolled back to a working state.
The business of cybercrime is changing. With the growing popularity of ransomware, we should expect a gradual decrease in time between a published remote vulnerability and your systems getting attacked. It may be useful to delay patches by a day to see if there aren't any glaring problems encountered by others - but it's not a reason do leave open holes that were patched in March. Frankly, there was no good reason why this attack hadn't happened a month ago; next time the gap may be much smaller.
Yes, there is a chance that installing a security update to break your systems. But there's also a chance that not installing a security update will break your systems, and that chance, frankly, is much higher.
Furthermore, "That can cause problems worse than leaving security issues unpatched" seems trivially untrue. Every horrible thing that might happen because of a patch broken in a weird way may also happen because of an unpatched security issue. Leaving security issues unpatched can take down all your systems and data, plus also expose confidential information. A MS patch, on the other hand, assuming that it's tested in any way whatsoever, won't do that - at most, it will take down some of your systems, which is bad, but not as bad as e.g. Spain's Telefonica is experiencing right now. What patch could have caused them even worse problems?
The business of cybercrime is changing. With the growing popularity of ransomware, we should expect a gradual decrease in time between a published remote vulnerability and your systems getting attacked. It may be useful to delay patches by a day to see if there aren't any glaring problems encountered by others - but it's not a reason do leave open holes that were patched in March. Frankly, there was no good reason why this attack hadn't happened a month ago; next time the gap may be much smaller.
Yes, there is a chance that installing a security update to break your systems. But there's also a chance that not installing a security update will break your systems, and that chance, frankly, is much higher.
Furthermore, "That can cause problems worse than leaving security issues unpatched" seems trivially untrue. Every horrible thing that might happen because of a patch broken in a weird way may also happen because of an unpatched security issue. Leaving security issues unpatched can take down all your systems and data, plus also expose confidential information. A MS patch, on the other hand, assuming that it's tested in any way whatsoever, won't do that - at most, it will take down some of your systems, which is bad, but not as bad as e.g. Spain's Telefonica is experiencing right now. What patch could have caused them even worse problems?