I'm a little in between, here. I've posted OC a couple of times, and I'm working on a new one currently.

I for one do think aesthetics should be part of it, absolutely. Having posted OC before, though,you will get a lot of pushback for aesthetic choices - if your colors don't perfectly interpolate or anything can be interpreted as not strictly accurate. There's a degree to which accuracy and aesthetics are at odds. For example, a pie chart can be perfectly accurate, but if certain colors are too similar or one color stands out without good reason, you will be accused of manipulating data or not presenting it honestly.

On the other hand, I also think some data just are beautiful, regardless of aesthetics. Interesting data are fun to look at on their own, and the data itself is part of the beauty, like "r/oddlysatisfying" I think sometimes a post isn't about the data visualization being beautiful , but the data itself.

Ultimately, though, it's a matter of voting, particularly on new/rising posts. Given that only about one in a thousand viewers or less of a post actually up or downvote, individuals have a lot of power to reshape the sub, by voting in new/rising. If more aesthetically-minded posts are lifted, the OC will follow suit.