...It remains a bit 'weird' if you buy the top model, pay a top price for it and then don't use all those extras you paid for....
-this can be said for every keyboard model.
I think, many are buying "better" keyboard than actually needed, and some just wish to have the best they can afford. For example: Many arranger keyboard owners never really created a style and so we could wonder, why didn't they bough some (cheaper) PSR-E keyboard instead. However, there's another aspect.. some features are simply good to have for "just in case" -especially if we know, that we can't afford to buy another keyboard anytime soon.
As for two Genos versions, where one would lack some features... I don't think that's a good idea. What features to take away? And how much price difference that would make? 10%? In that case, I bet, everyone would still buy full featured version.
However, if price difference would be quite bigger, then (depending on what features were missing), majority would probably decide for stripped version. But the thing is, even one of the two (same) keyboard has less features, it's production cost remains practically the same -it just means less income. So I don't think Yamaha would be interested in such scenario.
In that sense, I can imagine differences to be mostly on hardware side, i.e. 88 vs 61 keys, differences in back panel connections, etc. -that's what actually influences production costs.
And thinking further, I'm still surprised about substantial price difference between PSR-SX700 and SX900. And if something similar would happen with (next) Genos, I'm sure many would consider 61key option.
Just sharing my thoughts,
Bogdan