Greycap,
I think this goes far beyond personal tastes.
Those of us who have become involved in traditional music have done so because we believe it to be important.
While I agree with you that this thread has been poorly set up, if we are unable to discuss the abilities of public performances of singers and musicians for fear of hurting someones feelings, we may as well all pack it in and go home.
Analysis, criticism and discussion are an essential part of the well being of any creative activity; stifle them and that activity will deteriorate and die.
Taken to its logical conclusion, we would have to steer clear of discussing cinema, theater, painting, literature and any other artistic endevour. Healthy, positive critical discussion is the lifeblood of any art.
Jim Carroll
PS I would extend this argument to the parallel 'under-rated performers' thread; bland sycophantic praise can do as much damage as negative slagging off.