Backup is just good policy. You need the ability to back up data and applications someplace, so they can be restored somehow, to keep the business running in case of some natural or manmade disaster that takes the primary business-critical systems down.
We have whole industries that provide backup sites and backup technology. They can be passive, meaning that you can restore the site in a short period of time and get back to operations. Or they can be active (which costs more), meaning it can instantly take over for the disabled systems with current data and code releases—in some cases, without the users even knowing.
In the cloud, disaster recovery inolves a new set of choices that don’t look much like the ones you have for on-premises systems. The approach that you take should represent the value that the applications and data sets have for the business. I suggest that you look at the practicality of it all, and also make sure that you’re not spending more than the disaster recovery configuration is worth.