What I found out is the bank change does not occur independently of a program change. One must first set the value of the bank (LSB) and then change the program value. When the value of the program is changed then the bank change occurs also. A firmware update allowing for the bank to change independently might be a consideration.

I can hardly remember that any keyboard ever sent those two values separately in the way that you can change a bank but not the program. And there is no point in doing so. If you have a sound in bank A, number 6, you simply put the msb/lsb and program change data into the requested fields. Now, if you simply want to change the bank, for example from bank A to bank D, same number (which is 6 in our example), you simply set a new msb/lsb value for the bank D and the number 6 into the program change field. I don't see why Yamaha would change that in a firmware? It's not really that hard to repeat the same program change value.