PS3 has it's fair share or problems too, namely with the laser, and it's quite common too. The problem is, manufacturer's are rushing to get products out as soon as possible, to save on cost, and maximize profit. Missing the Christmas season is just not acceptable; the 4th quarter is where the moeny is to be made in console sales. To protract development another 6-8 months to get things dialed, would result in millions of potential revenue lost, and would add tens of thousands of dollars, if not, more in cost, due to protracting development.
With the 360, it helped initiate something even bigger: the next generation of Xbox Live. I believe Xbox Live has earned over $1 billion in revenue since its inception, and it's contiinually growing. A new subscriber every second, and it's the largest distrubution network of entertainment in the world.
Sure, MS lost money on the consoles, but the money they made on Live made more than up for it. MS is laughing to the bank. What's another console replacement, when every major network wants to get involved with your service?