Yeah, this is fair. Big Waaagh is generally going to be a bad choice for Kruleboyz only. Not only are the benefits not as relevant, but your Waaagh point generation will be comparatively very poor - not only with not having any units that contribute to it directly, but also ranged units are very bad at generating Waaagh points.
I'm looking into Iron Jaw and Kruleboy mixed Bug Waaagh though, and I think it has potential. Maybe not in competitive play, but as something that broadly functions and won't be just hobbled by its allegiance choice for pick up games hah
In that context I'm looking at it as an Iron Jaw core that holds the centre, with Kruleboyz bringing some range and mortal wounds than the list might otherwise lack.