Can't. The word you're looking for here is can't. The unit economics of making the sorts of games that JV makes completely preclude it. It would be way easier to spend the money he doesn't make to get better art talent. This is true. It is also not very meaningful.
And it's not that there is minimal sense of direction just for funsies--it's that you don't have that luxury when we're talking about the rates he's working at. I spent a decent amount of money, in the ballpark of what JV probably spends on third-party work for a game, trying to get freelancers--reasonably priced or, in reality, not so--to work towards a cohesive art style. That I did not ship that game (which is still in a 75%-ish complete state in my graveyard, it's my fuck-you-money project) is largely due to the difficulty of getting art to a standard I felt comfortable with.
JV ships because that standard is lower than I was able to stomach.
His games also happen to be really good, too.
You can go offshore for cheaper, but then you introduce risk, and if nothing else, JV's model is to minimize risk as much as is possible.
http://jeff-vogel.blogspot.com/2009/03/so-heres-how-many-gam... covers "Geneforge 4: Rebellion" (tl;dr: average performer, $120k budget, almost in the black after 3 years.)
He has a really good GDC talk that goes into more detail and might shed light on why he operates the way he does: https://www.youtube.com/watch?v=stxVBJem3Rs
[0] https://www.kickstarter.com/projects/619141553/queens-wish-t...
This stuff is really raw and really hard at the margins and tolerances we are talking about here.
I think the real term is "Not Invented Here Syndrome".
This site has thousands of open sourced game assets: https://opengameart.org
Here is an asset pack of 65 fantasy icons for $5: https://assetstore.unity.com/packages/2d/gui/icons/fantasy-r...
I suspect someone spending $200 and a day of searching could probably find most of the art needed for Queen's Wish. There's really no need for him to be hiring freelancers in the first place.
Simply saying "just buy cheap assets" completely misses the point here.
You can't make everybody happy. JV is going to more reliably make money by making his audience, like me, happy. Why should he change it?
It's a full-time job to find this art in the first place, to resize, to animate, to recolor, and apply effects to the art to help it match your desired aesthetic. And then it still is never good enough.
There's a lot to be said for having someone produce art to your requests in a consistent style, even if the quality of the art is not extremely high.
When you change your focus from a loyal customer base and change key aspects of your product they prefer in order to chase a competitor's customers you risk losing your own base and still not picking up a substantial portion of the rest of the market.
He compares it to Baba is You, and while that game's art is technically simple, its consistent aesthetic and style sells it.
Meanwhile, in his screenshots, the visuals seem dated and inconsistent. I don't think it's a problem with the quality of the assets, but in art direction, and like he said, that's on the developer.