I kinda see both sides.
The shadchan wants to know to be more on target which future shiduchim, and the one was told no wants an explanation to better know what they need in a spouse.
On the other hand, you dont want to embarass anyone, and if you say s/he is too frum or not enough, too quiet/loud etc.. the shadchan may go to the other extreme.
Often, after spending many hours with someone one on one with few interruptions you pick up on subtleties which when expressed in words may seem harsh or severe and taken the wrong way about both parties involved.