the reason why it "looks" too dark is because they left out the amber piece or cleared it. the contrast makes it look very dark. by keeping the amber piece, it'll contrast the headlights so it looks clean and simple still.
comparsion:
w/o amber:

with:
i think blacked out headlights on an 04 blue coupe would look real good. i done it to my enternal blue coupe and it turned out nice. looks even better with tints and matching colored parts (hood, wheels, grill, etc)