The reasoning can largely be categorised in 3 groups: 1. Attack: together we are stronger; 2. Defend: against Google, MySpace, Facebook et al; 3. Synergies: from better management and reduced costs.
I think people should not loose these things out of sight:
- Typically, large corporations destroy a lot of value doing deals like these (cf. HP/Compaq, which was all about Dell).
- Market shares cannot simply be added together. Advertisers want to shop around, as do consumers. Therefore, to say that a 10% and a 15% share add up to 25% is shortsighted. It will be more like 20%. (And so: the little guys in particular may benefit!)
- What is the message from Ballmer to the MSN/Live employees? Quite simply: "you suck". And should Yang sell out, his message is loud and clear too: "you totally suck". I wonder what that will do to the motivation of these people, their willingness to cooperate and their eagerness to innovate. It wil be virtually impossible to get everyone to work together, from California and/or Washington. There will be ugly fights over whose video platform, whose shopping site, whose brandname, etc etc will dominate and 'win'.