People distract themselves with silly things like bra straps and other unimportant things because...
1. Our society has been turned into nothing more than CONSUMERS. Things like this are made to seem important in popular media so that we will spend more money to " fit in" . Money truely is the root of all evil and woe.
2. It is much easier to concentrate on trivial things than to think about the real problems.
And 3. Because sometimes we make ourselves feel better about ourselves by judging others.
Coming from a Christian point of view, us guys like our girls nice and covered up. We don't want them to be very out-coming about their under-wear (not underwear, under-wear) and/or body. That's my view on it. And also it's tacky ;)
Not everyone would say so. Only those people who assumes that the women would not like it that way would advice to correct it. Others, who doesn't care for a stranger or who likes to enjoy the sight would not inform of the malfunction. And then, there are some who exaggerate the issue, and they are called conservative, for one or the other reason.