Further it's a ridiculous superpower if you're not a developer - it's so empowering for anyone on the business side with questions to just go look in the db.
Linus Torvalds: "Bad programmers worry about the code. Good programmers worry about data structures and their relationships."
IMO proper database design is extremely important. Code is fluid. You can replace it. Data is not that fluid, it's much harder to change it. Database should contain checks to ensure that bad data won't be saved.
I don't think that complete business logic should be in database. Keep data in database, keep your code in your application. Database is responsible for data storage and some data validation to prevent misbehaved apps storing obviously bad data. Application is responsible for everything else.
And it goes with what you're saying: changing a schema is not as easy as changing the code. So start by really understanding what you need to do, and then build the schema at the end.