Personally, I've found that understanding what the AI generates well enough to make substantial changes to it hasn't been too difficult, though it'll obviously depend on how complex the project you're working on is. Effectively speaking, it's like using any sort of off-the-shelf solution and then modifying that solution; you don't need to understand it to use it for your project, but you'll need to do so to make significant changes or add extra functionality.

Practically speaking, is there really a difference between prompting an LLM to create a CMS for a website and installing something like WordPress or Ghost? The setup requires no understanding of the underlying software, but you'll have to build up a mental model from scratch if you want to extend or modify it later.

Of course, it's not going to please anyone that likes the process of programming or knows enough to tell that the output is mediocre at best. But it's very useful for people that don't know how something works and want a 'workable' solution that functionally does what they need. It's basically the next iteration of the WYSIWYG web design tool, the CMS, the site builder, etc. A professional software engineer would be horrified by the code they output, but a non-technical manager type wouldn't notice or care.