It's funny, I've had similar conversations, where the agent would recommend the 'lazy' solution because the robust one took too long. More often than not, it was assuming human-hours of work though. Once reminded that a clanker would be doing the work it's conclusion shifted to the robust one.
Now, I wonder if it actually agreed, or if it sensed that I preferred the robust solution and was trained to make me happy.
Yeah, I've seen that, too. In my case it was less about the dev time and more about the regression testing time (much of which would fall on QA and involved reading from external feeds, etc - so, complicated). But your point is fair. The AI is ... notoriously bad at LOE. Not that it's always wrong, but frequently enough (and by a large enough amount) that tradeoffs like that really need humans considering them.