Having a bra strap continually slip out can be irritating. You want to look pulled together and not constantly tugging at your clothes.
A bra strap holder is a simple thing to sew in your tank tops and any other clothes that have narrow straps.
It use to be quite common to have bra strap holders sewn into clothes and it is one of those little things that manufacturers have stopped doing to cut costs.
It will only take a few minutes to sew these into your clothes and you will be feeling more pulled together once you have them.