It's Important, Right?
You need to look right!
Looking Bang On is a must when you are playing a character in a movie, to going for a ceremony and way other situations that are possible.
Costumes make the character look perfect and to the mark. There has to be proper costume research as per the necessity as per the Director's Visualization and as per the requirement of storyline and the era it is depicting. Perfect look of a character makes the audience concentrate on the storyline.
If Somebody compliments the costume too much then the stylist or costume desighner has gone wrong somewhere in calculating the costume as per the need of the story and the story has taken a back seat.
A good Costume Designer does their homework on the script, understands the changes, chalks out the USP of the character, discusses with the Director. So that the light, camera and the set blends perfectly with the character.