It's the same thing in other types of art as photography. I've seen a lot of technically perfect (well I think it's perfect, the artist sometimes thinks otherwise) art which aside from being very aesthetically pleasing I find otherwise really boring because there doesn't seem to be much else to it. There's reaons people sometimes like the sketches more than the finished pieces ;D
Haha! You might be on to something there, mate! Even when someone checks all the boxes, if something was done without being injected feelings in, it really translates to the viewer. I'm sure that even the untrained eye would be able to spot it. The sketches are honest, and peels back all of the modifications that would've been done to it. One could easily see the feeling poured into it through the raw lines. As an artist, I'm sure that you've encountered this many times!