I recently had an issue where a rogue process caused some ec2 instances to run out of memory and crash. It probably shouldn't have been an issue, except I was using t2.small instances which are pretty memory constrained and it ran out of memory before someone could respond to our monitoring alerts.
Obviously it's best to avoid using swap if possible, but if I had swap enabled my instances probably would have stayed online albeit with degraded performance.
Given that hard disk space is usually abundant it seems like a good idea to enable swap even if it's only required in exceptional circumstances.
By default OpsWorks only enables swap for micro instances, not small instances. Why would they be so conservative in enabling swap, is there a reason I might not want to enable swap if I don't need it for normal operation?