The same incentives that discourage good code in pre-AI times are still dominating now. You will be pushed to ship sub-par products in the future, just like you were in the past.

AI certainly has the potential to make the underlying code/design a lot cleaner. We will also be working with dramatically more code, at a much higher rate of change. That alone will be a big challenge to keep sustainable.

The ones making the decision to under-invest on design are either are unaware of the real costs, or are aware and are deliberately choosing that path - that's not new, and I don't expect it to change.