Dignity Begets Modesty
When God dresses you he dresses you better than you could ever imagine to dress yourself. The reason very simply is that we always tend to apply less dignity and value to ourselves than God does, at least in the ways that matter the most.
One trend that you’ll find in the scriptures is that where it is not cool to be wearing fancy clothes for the purpose of showing yourself off, but there are numerous times where it was very cool to be wearing fancy clothes when someone else was showing you off. Same value but in one case you are valuing yourself and in another case someone else is doing the valuing. It seems like it takes an outside force to re-write the stories we live.