In this game of work/development, you can't make sure that other humans don't "cheat". Our work won't compete anymore with other human's work, but with a computer.
Well, for the same reason playing chess vs a person is more fun than doing chess puzzles, if we follow that analogy.
Also, creating something with AI doesn't really feel like you made it yourself.
And, if you make it without AI, most of the times it feels pointless, why spend 30 days on working on something that can be done faster and better in 1 hour?
I am not saying about doing things for fun, but about creating useful things.
Yes, you can do "hand-crafted" things, and people appreciate that, but for code, people aren't able to see the craft anyway.
I mentioned this in another comment, but we are social animals, we get most joy by sharing what we have created. And the problem now is that it's getting very hard to share and discover genuine creations vs AI-generated ones.
It is, if you are trying to sell all of them in the same market, so 99 stalls with mass produced stuff, one with handcrafted stuff, but you don't know which is which.
You can play PvP in those games. Not really the same with developing software. In fact, not using ai would probably make you lose if there was some “software PvP” mode or development.