Think of all the superstitions players have about dice rolls, when the reality is that random is just random.
Spoken like a true heretic. Remind me to burn some incense and chant the Litany of Cleansing to purge the corrupting impurities from my mind before picking up my dice bag again.
OT: Interesting that in the entire piece you didn't talk about the start of the campaign and character creation. From what I can understand of the column, the theme was chosen by the GM and planned ahead of time, but you didn't mention that a character with no interest in the theme is a character unsuited to the campaign- the classic "Barbarian in a political game" problem. If I'm running a campaign with a specific theme in mind, I make sure to bring it up during our character creation section and encourage PCs to have some tie to it. For war, I might suggest that family members got drafted or signed up, their home was destroyed or annexed in the fighting, that the character attended a military academy in their youth, etc.
Not everybody needs to have an obvious link or a character built around the concept, and details can certainly emerge as the campaign goes on, but like you said: a theme is a background event, one that will have influenced the character in dozens of tiny ways long before the campaign starts.