Not sure how/why you didn't get my reply:
If your offsite backup server has enough space to accommodate all backups that your retention period requires, backing up WAL archives is always a good idea as it could not only help you restore the standalone database, but also allow you to set up a slave if need be.
Another way to think about it would be a backup without WAL files would be ideally just a base backup, while the one with WAL files will give you point in time recovery. It all depends on what you want your backups to be used for.