Is there a reward or something for completing bonus on Death Wish mode?

[Arcana]

Maybe I didn't pay attention, might be missing something... is it worth it to try and complete each level bonus? Some are annoying. If there's no point in trying to achieve each one I might as well just complete main objectives.

[The Void Boy]

I'm pretty sure the only thing you get from getting all the death wish stamps is an achievement. So it's entirely optional.

[TickTockStar]

Aside from the Achievement, it's still a good idea to go after the bonuses aswell. They count as stamps, and some Death Wishes need a certain amount of stamps to be unlocked
Seal the Deal being a popular example, requiring 70 Stamps to unlock