Darcy may have gone to the ball to provide some "objective" feedback on the neighborhood, since Bingley trusts his judgment and Darcy wants to be of service to his friend in that department (aka looking after him). (From Ch. 4, we read: On the strength of Darcy's regard Bingley had the firmest reliance, and of his judgment the highest opinion. In understanding, Darcy was the superior. Bingley was by no means deficient, but Darcy was clever. )

Darcy did give feedback on things (although whether objective feedback is questionable, since Darcy was the object of observation and annoyingly (for him) he was expected to participate in the festivities rather than merely observe.)
His observations were (Ch.4):
Darcy,... had seen a collection of people in whom there was little beauty and no fashion, for none of whom he had felt the smallest interest, and from none received either attention or pleasure. Miss Bennet he acknowledged to be pretty, but she smiled too much.