Let's be honest: if you're using legacy test approaches, you spend a ton of time maintaining your data-driven tests. And that time slows you down when you're trying to keep up with a dev team that thinks, "We're coding to standards — it should all run everywhere."
Think about the most difficult parts of coding and maintaining your test infrastructure. The simplest part involves writing the initial tests. You use what you see and your understanding of expected behavior to drive the tests. Test maintenance costs can drive you crazy.