Enable the ability to Show / Hide the commenting functionality for each card.

There are too many "comments" icons on a board. This makes is easy for users to get confused about where to add comments or where to find comments that were previously entered.

If you could "toggle" the comments function for each card, then you could limit a board to only 1 place where comments can be added--making it much easier for end users.

Also, the ability to add an instructions icon like the below would make it easier for people to find where to add comments.