You ask a predominantly elderly bunch of 61 note arranger players, or refugees from home organs (which had either 61 or even 49 note keyboards) what they want, you are ALWAYS going to get '61' as the answer.
Yamaha already THINK they are catering to 76 and 88 note players with their watered down arrangers posing as home pianos (despite being functionally identical to 76 arrangers, albeit crippled ones), and probably have the attitude of 'if you need a better arranger, there's always the Tyros or PSR line'

It's like asking a bunch of motorbike riders whether they want a four wheel bike... They already MADE their decision to ride bikes, a LONG time ago.

If Yamaha want to do some REAL market research, they should ask owners of 76 arrangers from OTHER brands whether, if they made a GOOD 76, would anyone buy it..? I think they would find a COMPLETELY different answer than asking people ALREADY happy with 61's.