Because all of the cables run back to a Central Wiring Panel the homeowner can easily change how and what individual cables are connected to and what they are used for.
Each cable can be individually isolated and tested for shorts and opens as need be.
Splices are prone to failure and can pickup noise and interference and, quite simply, are not needed in a Structure Wiring system.
With all cables running back to the Central Wiring Panel they can all be connected to the same source and access the same signal level.
This is one of the main reasons for installing a Structured Wiring system. with multiple PC's in a home the homeowner will want the ability for all the PC's to be networked. Network PC's would allow a number of things to happen.
The ability to have multiple PC's sharing a single internet connection.
Having the ability to access files located on any of the PC's hard disk from any other PC.
The ability to use devices such as scanners and printers from any of the PC's.