Is idempotency in API design a must-have, or is it just too much?

ive been thinking a lot about idempotency lately, esp when designing RESTful APIs. it seems like a super important concept for making sure things are reliable, particularly for ops that might be retried bc of network issues. but, making true idempotency work can add complexity to the backend. for non-critical ops, is it always worth the effort, or are there scenarios where we can be a bit more relaxed about it? what are your thoughts and common practices here