The biggest problem with the 'win now at any cost' philosophy is that it doesn't guarantee anything. Look at the Tigers, who took on some big contracts and sold away their farm. They had a good run at making the postseason, but won zero championships. Now, it appears that they are going into rebuild mode, which is usually inevitable after sacrificing the future like that. If you go all out and come away empty, then it really hurts.
However, if a team does end up winning a World Series Championship, which the Red Sox did after the Iggy trade, then that changes the entire perspective of the trade or trades. After all, that's the whole point.
That's not saying that I agree with the philosophy of winning now no matter what the cost, but if you do win the championship, I think it makes it worth it.