LLMs will give responses based on data that already exists. There's plenty of data that allows an LLM to write working code - possibly even high-quality code! But there's not much data that says how to make a "great" app, I think because it's domain specific.

Consider:

What made Firefox great was the lived experience of people fed up with IE6. The Internet talked plenty about speed, tabs, and stability, but "speed, tabs, and stability" undersells much of what made Firefox stand out.

What made Ocarina of Time great was that it defined a genre. No one really knew yet whether the story, the graphics, the dungeon design, or the marketing was going to sell that game. You couldn't yet ask any other Miyamotos what had worked for a 3D adventure.

We still arguing over what made Tom Brady (the American football player) great, not being able to nail down if it was the length of his career, the number of times he won the Super Bowl, his individual game records, his coach, the rest of his team, or something else entirely.

I think, likewise, the criteria for a "great" app aren't known until the app is already great, and that gives an LLM no specific advantage.