I just don't accept that the death of a parent is somehow an obligatory part of every fictional character's backstory. That's too formulaic.
This is true. A character is more than able to be fully fleshed-out and sympathetic without the death of a parent. But it's not inherently objectionable, either. In the context of MoS, I think the death of his father is an especially significant moment - regardless of whether or not that moment was effectively portrayed.