Of course Yamaha listens to their customers. thats exactly why they are market leaders in this product class. They dont make 76 Keyboard size arrangers because it is a niche market and one they dont want to play in. If they could make the profits from this market that they could in the 61 key market they would produce 76 key arrangers .
They are not stupid or stubborn. They are customer focused. They know who their core customers are . You may not be their core customer customer . Yamaha knows that there are some potential customers that they will lose because they dont offer a 76 key version of the tyros but thats a calulated loss. They are focused on the core purchasers that are fine with 61 keys and who are likely to switch brands if the board is made any bigger. There is no point in offering all sizes to everyone because there has to be big enough profit margins from each of the markets . Clearly there is not enough in it for Yamaha or they would most certainly make them.