Firstly, we all know how slippery a wet soap bar can be and nobody wants to be hunting around at the bottom of the bath or shower for their soap bar!
Not only will the bags keep your soap bar safe, but it's also a great exfoliator leaving the skin softer, brighter and improve circulation at the same time. When you've finished just hang it up to dry and no need for mucky soap trays
You don't have to use it all the time if you don't want to, but maybe when a soap bar gets so thin that even a gentle rub breaks it into ever-smaller pieces, its easy to transfer the pieces to the soap bag. This collects all the smaller pieces so that you can use them without worrying they'll slip through your finger and down the drain.