Sooner or later competitors will release similar functioning software or advanced forks therefore Wasabi Wallet has to innovate and stay ahead. This is another step in the right direction. In the end, if the improvements continue it is only going to help the end users because they have more options within the app.
SLIP39 integration is coming to Wasabi in the next release - https://github.com/WalletWasabi/WalletWasabi/pull/13800
But they will always need the Wasabi core developers for their own updates and other back-end innovations. The Forks need those core developers, and therefore they will need to incentive them sooner or later.
Plus if the Forks believe that they could continue development of the code, and actually does produce better code than the Wasabi core developers, then Wasabi will simply copy the code because it is Open Source.