Bridesmaids dresses

I read somewhere recently about a bride who only asked her bridesmaids to wear pink, no shade or style specified. It allowed each woman to wear something that they felt attractive in. They all carried the same bouquet and wore the same shoes, which tied the group together. I think it's a good idea--I'm all for bridesmaids dresses that actual flatter the bridesmaids. I would worry, though, that someone would pick something a lot more formal or simple than the rest, and wind up looking over/underdressed.