There is an additional forum tool no one has mentioned, the private message. I can totally see a poster reaching out by private message to another forum member and asking for critical feedback. My guess is the respondent will be so flattered to be asked their opinion that they will take the time needed to give a more considered opinion.
David, you mention a songwriter's section but what about other song facets like arrangement, instrumentation, recording and mixing? Where does it end?
Howdy Jim....
I think that's a very good point to mention.
If one does approach someone in that manner they've obviously listened to some of their material and thought highly of it enough to ask for academic and creative critique.
A more 'considered' opinion...AND/OR...a more
candid one.
Understanding the positive intent by David it will always be a dual edged sword.
Many who desire honest feedback aren't going to hear what they want to hear from many commenters.
Hence....I'm very selective about which songs I
may decide to comment on and choose my words carefully.
If my opinion of a song does not match with the masses (which is frequent) that have already commented I keep my mouth shut.
We're all adults here and likely want to improve on our song writing skills.
So....gratuitous, patronizing 'atta boys' (especially in this context) doesn't work for me.
Besides....someone may listen to one of my songs and think "what do you know, your songs suck"

Song writing is very personal creative endeavor.
As I've mentioned many times over the years....one must have
the skin of a snow tire if one chooses to put their creative efforts up for the world to hear.
We have to accept ALL comments whether complimentary or critical regardless of the personal subjectivity (which is OK) from the source.
We should have no expectations when we upload a song for others to hear.
As far as the newly suggested forum addition?
I'm mixed. (no pun intended)
I wish all the best in their song writing pursuits.
Have a great day everyone....