Speaking from a 'my art is crappy IMVU edits so it's never gonna be in the realm of reselling but I have some thoughts' point of view. I don't agree with reselling for a few different reasons but firstly from a practical standpoint because it becomes difficult to legitimise proof that artists have given their consent for their artwork to be resold. I think it opens a world where people can be profiting from someone else's art without the artists consent and that buyers may fall into a trap of purchasing things without fully checking that is actually responsibly for sale.
I also believe that it can make tracking artwork difficult for an artist. Let's say the artist sold their artwork to person A and has in their rules that reselling is allowed, 10 months down the line person A resells the artwork to person B and the artist isn't aware and then sees person B using said artwork and files a DMCA violation or approaches this person for using their artwork without permission. I understand that it's an artist's personal choice but I personally wouldn't like not having awareness of where that artwork was.
Finally, I think in allowing resells artists are handing out a fair amount of trust. The initial owner still has that artwork with their text on it and what is really to stop them from using it again in future after reselling it? Also, when does a reselling chain stop? Can person A use it for 6 months then decide that they don't want it anymore, sell it to person B who uses it for a few weeks then doesn't seek the original artist's permission to resell again because they got it through a resell initially so they then resell again to person C etc etc. How many people in the end have access to that artwork? I know it's an extreme example but it's risky to me.
I'm sorry that this isn't very articulately written, my fingers are cold so I can't be bothered with proper grammar and such. I also am aware I come across sounding very 'I am anti-people, I don't trust people' but well some people suck.