This is a really good quality list! A lot to think about.
"catapult pipe shouldn't need another worker": I was thinking of this one, I thought the pipe was a strong upgrade and needed a downside.
"I'm really reluctant to build new things or upgrade near the earthquake": The first idea behind it was to have some sort of 'prestige' that a lot of incremental games have. At the same time, building getting destroyed might be annoying for some.