Question marks aren't strictly necessary in Chinese and Japanese since meaning can usually be inferred from context. Meanwhile, Spanish takes a more explicit approach, proactively including a ¿ at the beginning and a ? at the end of a question. And, of course, many languages opt to only include a ? after a question. Given how differently languages treat question marks, it's unclear how necessary they are.
On the other hand, in English, lacking commas can lead to ambiguity which result in simple misunderstandings (e.g., "The panda eats shoots and leaves" vs "The panda eats, shoots, and leaves.") or even court disputes.
It's interesting that the need for punctuation can vary so widely. If I were to create a language from scratch, it seems like there should be less ambiguity as to whether punctuation is necessary when conveying information.