Excellent point.
We are teaching our daughter the same thing and she hasn't complaint yet.
Have you noticed that they don't make clothes like they used to?
I even have problems finding shirts that go lower than the midriff ,that are still fashionable and not to"old lady"like.I always buy my shirts and my daughters shirts one or two sizes bigger to cover the mid section.
Do a search for "modest clothing" on any search engine. You can also check out the LL Bean and other catalogs. There's plenty of modest clothing out there. The difficulty may be getting your daughter to choose it.
I have to do that, particularly for my daughter.........It's particularly annoying when trying to buy long sleeve shirts for this time of the year.....the sleeves are longer than the body of the shirt, so I wind up rolling up her sleeves in order to have a shirt long enough to tuck into her pants. and she's only 6!!!!!!!!