@scotland yard
Actually the term reactionary would probably be a misnomer for this discussion. The term usually refers to far more substantial matters then business practices. Needless to say we are both probably viewing the term in a rather bastardized form. Such is the way with words meanings change and get distorted through time.
I say Microsoft is being proactive in that they had their information and planned ahead accordingly. We rarely say we reacted to an event we fully expected to happen. Especially if it did not cause us to deviate from our intended actions. For instance if I am going to work one day, and I have known for the past two months that on that day the route I usually take will be closed off say for a parade. Obviously I have considered a different route to take to my destination. I would hardly drive up to the blocked intersection act shocked, surprised, and generate a new route on the spot. I foresaw the event, and had planned for it in advance.
Your really saying that Microsoft was reacting to the Sony price cut in February. That would be an effect preceding the cause. They considered the likelihood of what would happen at that time, and generated their own long term plan. Had they deviated from that plan in response to Sony. Then they could be called reactionary. However the did not. They decided on a plan of action far in advance and stuck to it.
Generally we don't say we react to situations we expect to happen. Otherwise we must say that everything we do is a reaction. I certainly do not say I am reacting when I go to pay my bills. I am being proactive I am sticking to a self generated plan based on available knowledge. That my car has gas in it, the offices where I pay my bills are open, and that I have the money to pay said bills. I am not reacting to these things. They just are, and my response to these things is not going to change. Unless they are not what I expect, and then I say I am reacting.
I suppose if you want to get technical you can class every action as a reaction, but then what meaning does the word really have, and more importantly would we actually need it.
I would have said Microsoft had reacted had they immediately dropped their prices, but they did not. Instead the spent over a month not lowering their prices, and then they dropped their prices in a fundamentally different way. Globally compared to regionally. Further more they were incredibly consistent.