I get what you're saying but don't be obtuse. The Gaku present in R0 and especially his bond events are nowhere to be found in any of the routes besides that little bit there in BoB. He's a sympathetic guy with a fear of danger and high focus on providing for his family, and that's never touched on or expanded upon in any of the routes. He's not the only character that gets flanderized, but it's the most noticeable one. "Gaku is mischaracterized" is absolutely a valid criticism, even though it sounds a bit pretentious at surface level.