MardleBum this is where fashion is so subjective - I really do think that with a beautiful pair of heals, some lipstick and a bit of sun on the day that dress will look incredibly cool and elegant but my idea of that is obviously different to yours.
It is quite an understated modern look but if you look at the trends and current look books for this level of 'aspirational LON/PARIS/NYC/LA' brand it really is 'what is in' - think Maje, Zadie & Voltaire, Claudie Pierlot etc. Don't forget The Kooples and the like are the brands that the highstreet copies.
Personally I find heavily embellished, longer, more traditionally elegant event style dresses (think coast etc) really tacky looking and would look awful on me but that is just my opinion!
In the end of the day all that matters is the wearer feels comfortable and happy in what they have on. This is the perfect example of how different everyones taste is!