"Lurking" is one of the reasons the site has diminished, in my opinion. For example, I posted some photos in the gallery at the end of April; so far, they have received 63 views, but not one single comment. If I was a new carver (instead of being an old fogie) posting my first carving and asking for advice, I would be disappointed and maybe even irritated. I'm not particularly concerned, as I've posted the same photos on two other forums and got several comments there.
Comments about a post or photo can be constructive criticism. Don't tell someone a carving sucks - tell them what you think might be an improvement; if you think it's great, say so. Most people will willingly accept constructive criticism, but no one likes to be ignored. If you are not comfortable providing constructive criticism out in the open, then use a private message to the individual.