GOG just updated their launcher to try to address this. If Steam needs an update to correct this problem, then Steam will have to release one. This isn't on the game at all.
These Files Are Compressed! Yes, typically the file will only take X amount of space on your drive, but when you are updating the game, it has to unpack those compressed files to install the patch data. No, there is no other way to interact with compressed files, without uncompressing them first. A few tips.
1. Your drive, along with ANYTHING that has a limit: Common Engineering teaches you should NEVER exceed more than 80% whatever that limit is for good reason. This is usually due for safety or damage mitigation reasons. Example: Your CPU can handle 100*C, but 80*C is usually the time to start to worry.
2. You should think of the game as really double the size that it actually is. These files stay compressed for good reason under normal circumstances, see Point 1, and in this case, that extra 20% if you read Point 1 will be more than enough extra space for you to install your patches.
3. If size of your SSD, yes, SSD is needed because these files are compressed, and it needs the extra speed to uncompress theses files when needed so you can play, and then put them back where they go, it is all very technical. If the size of your SSD is too small, consider getting a larger one... I am aware. You don't need to argue that because I know your argument, and there are millions of people who are in the same boat across the world. I get it. Another option is to get a cheap external drive to clear file space for the game on your SSD. I have a 3tb external that I got from Amazon for $60. This thing works perfect for a lot of games and files that don't need to be on my M.2 after I tossed my other drives. I love my case, but the slots are right behind the CPU, and that was a lot of heat. Anyways, don't think of it as spending another $60 on the game because if space is that big of an issue, you need it.