Good idea Tom...
Generally I am happy to receive comments etc. it's a way that I learn, even a 'nice shot but....' helps to gauge whether something is received warmly or not.
I see things that appeal to me and not necessarily to others but that's how the world works. It would be pretty damn boring otherwise imo; and I know that I have posted some mundane shots, sometimes as a way of gauging response and sometimes as in my 366 to get that shot in on the day....also, to try something different or new..I may try a different lens for instance; I have been using MF M42 lenses and have yet to try bellows for macro, they may not work and may not even get a comment, that's ok for me, some may and that may encourage me to carry on the experiments...
Hopefully, I try to be more constructive with my comments but must admit that I too have found that I am drawn into the 'Nice shot' mode..for me that is really affirmation of that fact that I like something without feeling the need to add anything else. I think we can like a photo just because it pleases us, it makes us smile, or it makes us feel warm, happy, and other such wooly nicey-nice terms etc......and does not carry with it a need to draw CC....
I am sure that there aren't many, if any members on RPF who would be unduly offended by good constructive critique, after all isn't it why we put our photogs up here, so we can share our photog experiences, good or bad, learn from those CC and others photogs and their CC etc.
I do think however, that because of the large number of posts that appear daily it can be difficult to go through all posts, (I know you do Hamish, but you wear your underpants on the outside of your trousers and cover your shoulders with a cape
) but for us mere mortals it can be difficult....
I wouldn't want to see RPF go down the lines of shoot because you can....Like my mama always said, 'sometimes, if you ain't got anything nice to say, just don't say anything....'