What about the cost of moving the logs to storage, and the infrastructure required to move them around and put them in storage? Especially if you have a micro services architecture.
Also the cost of the infrastructure to search the logs and view the logs.
Remember that there are different sizes of deployments. For sites like Reddit or Netflix, logs becomes a burden since there's so much data. For smaller deployments it's possible that all logs can be aggregated on a single machine quite easily, and aggregating the logs is far more enjoyable than SSH:ing to each separate machine.
> Sometimes logs can be useful, but only after your monitoring system has told you which system is not behaving, and then you can turn on logs for that system until you've solved the problem, but you shouldn't need access to old logs, because if the problem was only in the past, then it's not really a problem anymore, right?
Some things happen rarely, but can still have large impact. E.g. Imagine a once a day job of moving files which fails twice a month, rendering those files inaccessible.
Many shops don't keep logs around because we want to. We keep them because we have to. You might see things differently someday if you host data for customers and have to follow SOC2 and HIPAA requirements...
Also the cost of the infrastructure to search the logs and view the logs.