Centralization... or not?
There are two opposing trends currently taking place with motherboards: centralization, and decentralization. Here's an explanation:
The centralization trend is to place all peripheral computing functions, that is, the devices that the motherboard is connecting together, onto the motherboard itself. Most audio, video, storage and networking functions are thus run directly off of the motherboard, with rarely a need for “extension" or “plug in" cards, “daughterboards", or cables. This works especially well with fully integrated devices that are not intended to be pulled apart and modified and upgraded, such as most cell phones or GPS devices, or with cheap laptops. Having all peripheral functions integrated into the motherboard is more size and cost efficient.
The opposite trend is decentralization: more and more computing functions are being moved off of the motherboard and onto the individual pieces of peripheral hardware. This is due to the increasing consumer demand for more modular computers, that is, computers that are more customizable to the requirements of the user and not just a prepackaged assumption. Allowing peripheral functions to be moved off of the motherboard, thus, is a necessity with such modular designs. This also allows for cheaper repairs and upgrades, as the entire motherboard does not have to be replaced all at once.