I disagree, but your point is valid.
I find that a map is never truly finished. There is always a way to improve or adjust a map in a new direction, no matter how good it seems. A key example is all the remakes and variants of remakes that have been done so far in the course of Halo. No map is the same. For me, forging is about an ongoing process of crafting and tweaking a map to play the way you want it. I constantly go back, change maps, and create drastically different variants of them because I always think of new ideas or find a way to make something better, especially with aesthetics. Forgers always find new ways to implement game types and minigames and bring to life new features, even without constant updates.
Forge constantly getting updates does dishearten me a little bit, as I know there will be more things for me to do in the future. Maybe one of those things might work out better for me or a map I am making. I like to take that as a challenge though. In fact, I would rather have a map be stuck and all of a sudden work because of a new feature than never have forged that map. I want to find new ways to do things, even if they are considered the hard route. It is the weird things, and the workarounds which make many forge maps unique, and allow them to stand out in the community. People remember the odd and unique things in maps, and that's always something that I try to bring to a map. If you ask almost any Halo fan about elephants, they will tell you about the times they had on Sandtrap. Think of all the ways people have tried to recreate them in Halo games. Over time it has gotten more possible to do that, but people constantly work towards it.
Forge will never be static, and that's the point. It pushes the boundaries of our creative minds, and allows us to form things never seen before. It is innovation: using things that have never been used together, and using things in new ways that draws me to forge. It is this reason many maps are left unfinished, or are just a playground of my ideas, but the fact remains: I made my ideas come to life.