I also don't agree that the list should consider demand, it's up to each user to decide how they value the pet's demand. A few days ago I found an user that valued pets COMPLETELY differently from me. I'm sure that they wouldn't want to follow a list with my values and I wouldn't want to follow a list woth theirs.
Also the grinner doesn't have bad demand at all, during the past few months I had at least 8 and traded them all off easily following their list value and got overpay on 2 of them. The grinner's bad demand is 100% a myth