This is "signaling." Companies are not allowed to meet and align their strategies. E.g. car rental companies can't get together and agree to raise their rates 10% next year. (A few years back I think Budget got in trouble for basically proposing that other car rental companies follow their lead in raising rates in a conference call). However, companies can send each other signals in various ways. Microsoft may have been trying to send Sony a signal. If Sony agreed, consumers would have had to suck it up and deal with it, or refuse to buy the products.
So, Sony doesn't want to play along. It's probably a bid for market share more than a bid for consumer happiness, in my opinion.
Motivation? In other words, a focus on market share seems to me like it's a much more selfish thing, and that Sony is perhaps only going in the direction that they are because they perceive that it will be better for their bottom line in the long run and not because they care whether or not their customers are happy. It's hard to see how they would not be the same thing, but at the same time I think there is an argument to be made that there have been times that Sony have done things that decreased consumer happiness (e.g. removing the ability to install Linux on the PS3) which did not have a particularly adverse effect on their market share (how many people actually stopped using PS3 or decided not to buy one when Sony made this decision? I do not actually know the answer, so my argument might be way off base, but I had the impression that it was some insignificantly small number).
So, Sony doesn't want to play along. It's probably a bid for market share more than a bid for consumer happiness, in my opinion.