Let me clear up something real quick. Having dedicated servers or P2P is a choice of the developers. MS offers a matchmaking service alongside a ranking system in the form of TruSkill. They also offer leaderboard services across the platform. It is up to developers as to whether they want to use dedicated servers or not. L4D and L4D2 are examples of games that use dedicated servers. Forza 3 also uses dedicated servers and is first party. Hell, with XServer, external people can host dedicated servers for 360 games.
As for custom content, that is up to the developers and how they want to implement such a thing on consoles. Halo 3 took a step in a nice direction by allowing custom map variations and game types to be easily made and distributed through Live and Bungie.net. It is only a matter of time before the systems become a lot more involved in how they allow custom content to be created and shared.
The good thing about MS's matchmaking services are for developers to tap into an already developed and available system for online play. XNA developers can even tap into MS's scalable matchmaking services. No need for the developer to pay for their own servers.. Because of this need for scalability and accessibility available to ALL developers, there is no telling how many servers MS has on hand to maintain such a system. Not only that but there must be employees to handle any service availability issues, issues with particular games(such as the recent CoD MW2 glitch that MS is suspending people for exploiting), server maintenance, etc.
They are also now adding a few extra benefits for Gold members as well as online play. 1 vs 100(with more Primetime content sure to come based on its success), some new online services, game discounts, early access, etc.
Surely, the $4 a month it costs is more than the maintenance costs, but I find a ubiqutous set of services platform wide to be a compelling reason to partake of a Live Gold membership.







