This topic has been addressed before in this thread:
https://steamhost.cn/steamcommunity_com/app/453090/discussions/1/1743386555596063894/

I'd like to bring up the discussion again, hoping for a better outcome this time. About the last thread, It's unclear whether the request was denied, ignored or if the the last adding discussion were never seen.

Last argument against this suggestion:

Originally posted by Sebioff:

Build Challenge entries can still not be updated since it would allow submitting blueprints containing items that you would normally not be able to build in the challenge.

This is of course a 100% winning point during an ongoing challenge and reasonable even a month or two after it's finished. Keeping themes structured and whatnot. But now we're at a point were things have changed so much within the game that some blueprints are simply outdated. Whether it's errors or better versions.

I'd love to do some reworks of my old builds, but uploading them as new blueprints just isn't as "nice". And doing that, only a handful of people are going to get these updates anyway so it feels pretty pointless.

There's more to it, but it's already in previous thread, mainly this post.

I enjoy fiddling with the workshop and do a lot of experimental designs here (as it's free to be weird) But being unable to update a lot of the content makes me prefer deleting it, and that's not great either. It just makes me less motivated to make new stuff and so I'm having less fun in Parkitect, which I'd otherwise consider one of my favorites.

This is of course my personal experience, and I get this isn't a widely requested change. But I'm thinking I should be safe to ask assuming it's low effort change to make if you decide for it.