Man. I like it too.
And I love that in the end, the 'winning' paintings aren't... no, how to put it.
I like that they're portraiture. Beautiful portraits, but portraits. Representational art of specific people, without much stylization- in fact given that they are done in the same style as the rest of the manga, we can assume they are photo realistic art. Which takes a lot of skill, of course. But it's also not the kind of 'art' we see him make a lot of either.
It's the kind of art an artist like him makes for practice, to hone his skills, for comissions. It's one of the most enduring, universal, ancient forms of art. Looking at someone, knowing someone, and putting them to pigment and surface to say there was this person and they were like this.
And he painted them all happy. At rest. Makes me cry, man.