It seems like if you say "because of MW, I ought to anticipate all possibilities to be actualised", you have to include possibilities such as "suddenly and apparently inexplicably undergoing the most extreme torture a human being can undergo" (as well as the inverse - but, really, we know they don't cancel out), so if that were the correct interpretation of MW, it wouldn't be a reason not to fell fear (although, yes, perhaps the fear of death in particular would go out the window).

However, it doesn't seem like that is the correct interpretation of MW, because not all apparent branching points are in fact quantum branching points. If someone offers me a choice between orange juice and apple juice, and I prefer orange juice, I shouldn't anticipate choosing orange juice in one universe and apple juice in another. I prefer orange juice, so I choose the orange juice.