I have the same problem. My hair is naturally really dark ash brown and I hate it because it makes me look so dull and serious. :/ I've been a happy blonde for couple of years now and I think it's been good until I bleached highlights into even lighter blonde. Now they stick up and are flat and it really ticks me off.
Isn't there anything you can do for your dyed hair to make it healthy? Is "not dyeing" really the only option?