I'll always take a blank tile over blank cardboard, but I wish publishers would give an actual tile.
I hear ya! However, I'd caution that adding something just because there's room shouldn't automatically be done either. I'm sure that all the cardboard elements were play-tested before sending them to the manufacturer. So the lay-out isn't known until after this point, which means that anything added at this point would either not be play-tested (and could potentially ruin the game, necessitating house rules) or would delay the game longer (which means that the developer would need to pitch-fork and torch proof their HQ).
Having said that, I do wish they would have just gone ahead and added the trap token that was (intentionally) omitted.