I tend to be quite critical to "what we get for the money" and so I'm not defending Yamaha (or any brand) in this regard.
Of course it would be nice to have a variety of better styles onboard, but making a good style costs money. Not only that: as soon some style becomes similar enough to some original song, that involves possibility of additional costs (licensing, fee per sold piece, etc.). Needless to say that all hardware manufacturers are avoiding such "unnecessary" costs.
As you can see, I'm relative forgiving about quality of onboard styles -because if needed, one
can make his own styles for free.. or download them from somewhere.
Voices on the other hand, are totally different story. If we wish to have better than onboard voices, not only we need to pay for them (at least for good ones): we are also quite limited with amount of memory available for voices -ok, Genos doesn't really suffer space shortage.
Anyway, if I buy keyboard with "bad" voices, I can't avoid additional costs later... or I must simply accept what I have. And because of that, I will never tolerate bad (or not "good enough") built-in voices.
But yes, arranger keyboards are expensive and so we also expect a lot for the hard earned money we pay. But then, there's always "my next keyboard"
Greetings,
Bogdan