Yaguchi was set up as being the one that came up with Minimoni back in... 2001? Was it? We'll never know if she actually did or not. And it was during MM's golden years and H!P.
Naming someone sub-captain is definitely not the same thing. Reina naming Fukuchan and Haruna sub-leaders isn't even the same thing. If Captain would suddenly say "Berryz will only do RnB from now on!" that would be about the same level.
Reina said there on the show that she's been yelled at before for being stubborn and wanting to get things her way so she doesn't do it anymore. The new three girls have no seniority at all so they wouldn't dare to. So they do what they're told to.
Reina has no idea of how band-business works, which doesn't give much either. Yuki seems to, a bit, but she's still a newcomer so the seniority problem is still there. Reina is the only one of "authority" and she has been raised within the company in a way that she's not supposed to go against those "who know best." Typical Japanese mindset, really.
It's just really damn sad.