I look at it from a different angle. If you need the ability to recover from a catastrophic error by recovering a database to a specific point of time, then you have to do log backups. If you can't to lose more then just few minutes of data and doing full/differential backup might take to long, then you have to do a log backup. In that case you should modify the database's recovery model to full or bulk-logged (again it all depends on your business requirements) and start working with log backups. On the other hand if you don't need the ability of recovering a database to a specific point of time, and you can afford to lose data since your last full/differential backup, then you can set the database's recovery model to simple and forget about log backups. In any case I suggest that you'll read about recovery model and database backup and restore before you'll make up your mind.

Adi