All of us are always learning, whether we want to admit it or not. A master still learns, because each thing we learn opens new horizons beyond which we have not yet traveled. So the egoistic notion that "I've learned all there is to know" is just that, a function of ego. It's us protecting our self-image, often at the price of holding ourselves back from learning something that would benefit us. And part of the process of learning CAN BE listening to the feedback of others as they view or consume the creations we've put forth into the world. You can read, study the works of others, take classes, and it all can and does help. But feedback provided by the people who view our work can point out things that we as the creators were too close to see. "I was up to my nose in this work for 3 days ... and I totally missed that." So I certainly think that providing feedback to artists about their work is an appropriate thing to do, so long as it is done respectfully. And to that end ...
Feedback vs Criticism
I grew up in a time when the common belief was "criticism is an important part of the artistic process" ... and many people who called themselves critics loved nothing more than to lambaste the work of an artist, essentially spelling out all the ways in which the art in question was "wrong" ... where we eventually come to understand that "wrong" means "not what the critic prefers". I gradually came to see that art is a SUBJECTIVE thing. 2 is always 2 ... objectively. Art is the act of taking something of the soul and expressing it outwardly into the world with some mix of craft skills applied to objects or experiences. And it never hits two people quite the same way. What it meant to the creator WILL vary from what it means to every viewer, because meaning is subjective by definition. It is OUR POINT OF VIEW ... not a subjective fact. When critics provide feedback that essentially boils down to "I don't like it because it isn't what I prefer", it is essentially useless unless the critic commissioned the work and is redirecting the artist to correct the ways in which the creation does not meet the specifications of the commission. If you didn't commission it, you can't say it's wrong because self-expression is subjective, not objective.
That said, one can say that some works of a given artist seem more effective in conveying their intended message than others. I can look at 100 works by a given artist and see that some more effectively convey the themes on which the the artist is focused, and if I am learned enough to understand why, I could provide feedback to the artist along these lines. "I sense in your other works that you're expressing "X", and in this work, I see much of the same, and yet it seems to me that if (this or that change in lighting, point of view, contrast, etc.) was changed, perhaps that spirit would come through more powerfully." This is an artist or viewer respecting what the artist is trying to say and providing feedback about how effectively they THINK a particular creation hits the goal of conveying those ideas or feelings. IF the artist is open to that sort of thing, it can be a great opportunity for learning.
But not all artists are ready for that sort of feedback. It's not criticism ... it's not someone saying "I have different values than you, so change yours and I'll be happy" ... it's someone pointing out options they feel might allow the artist to do more of what they seem to be trying to do. That kind of feedback can be very helpful, if presented respectfully.
We as potential comment makers should also keep in mind that some people aren't interested in our point of view on their work. Could be sensitive ego, could be they aren't quite confident enough in their skills to accept feedback without it feeling like criticism ... or ... it could be that for them the raw act of expression is what brings them joy. While some artist love refining and perfecting their works endlessly, others genuinely start disconnecting from their work as soon as the initial explosion of self-expression has played itself out with their media of choice. Both approaches are fine, as are zillions of shades in between. We shouldn't assume that an artist wants to tweak their art just because WE would if it was something we were creating. They might in turn look at our work and consider it "over-worked" ... too refined ... to the point where the original inspiration was lost. I once saw an original sketch for a famous painting and fell in love with the sketch 10 times more than I ever did with the painting. The sketch was less refined and less complete, but it was so alive and fresh with the raw energy of inspiration. I loved it. The very refined and professional painting was very excellent ... but it had lost a lot of the power of inspiration as layer after layer of additional choices were laid down over the sketch.
Provide feedback with great compassion to artists. First, check to see how they respond to other feedback ... are they looking for and happy to get it, or are they a bit stand offish about it. Do they actively seek the insights and points of view of others or do they seem to avoid and resent them. Artists are doing something many humans never do when they take a bit of their inner self and share it with the world in their creations. Please respect that act of personal courage and comment accordingly.