Then to add to that mix, you have the problem of risk aversion, then a whole slew of other stuff that isn't im@s related, but affects im@s anyway. (But unless you care for things such as demographics, trends, market share etc, you probably won't believe anything I'd say anyway.)
Adding new elements is a risk - and with risk you include loss.
It's stupidly easy to say now "Well, adding in the guys as idols was a stupid idea due to the backlash." mostly due to the fact that we know the result. Try figuring that out in 2011, when you're told 'Okay, now you need to come up with something new, oh, and if you get it wrong, you're fired and you're out of the industry cause no one's going to trust you.'
If anyone realistically says they can do it, then in no uncertain terms 'screw you and the high horse you think you can claim, because if you're demanding the ability to see the future as a requisite to doing a job, why the hell would they be game developers? They'd be playing the stock market, or the lottery and be making a killing there.'
So with risk, comes with rewards, but with it, comes the ability to incur a loss.
Given the costs, and the current state of NBGI and the industry as a whole, playing conservative and securing what you have is far more beneficial, because the changes would only net marginal gains, and would incur significant risk.
Like take for example pairing switchups - how many more people would you seriously expect to gain? Then take the opposite - how many people do you think you'll tick off?
(If you haven't realised yet, it's surprisingly negative.)
Now, if they changed a LOT in one go, they might have significant gains, but then again, they could suffer what happened re: im@s2. Of course, experience says they got burned significantly on that one, and like any entity, they rather not get burned twice, at least so badly.
Incidently, I'm still looking for someone who's based in Japan - I require a proxy to do some purchases, and will commission as per negotiations.