yes it's definitely something i find very annoying, and I always avoid people who have a super restrictive tos like that. once you sell or trade a character it's not yours anymore and the new owner should be able to do whatever they want with it. i dont trade characters much anymore but whenever i do, i always really like seeing the new creative ways people interpret the character, its always exciting for me seeing how people work off of the design i gave them and i really dont get the mindset of,, not wanting that? i mean it's like if you want the character to stay the exact same and have complete control of them why even sell/trade them in the first place right??? i see people who have these hella restrictive tos and it literally just seems like they want get money/a new character/art without actually giving away the character, bc they have so many rules on what the new owner is "allowed" to do. which honestly while i don't think this is the intention it just strikes me as selfish and pretentious, it's like they're not really giving anything in return, and what makes them think they have the right to be so controlling over a character after they don't actually own them anymore?
the only thing i can get is not wanting the buyer to sell the character for a higher price if they don't make additional art for them, because then the buyer would just be profiting off of your work.