The reason for dedicated device is quite a good one: Customer service.
Home automation installers will stay well clear of devices that customers have the ability to customise. This only leads to headaches with devices not functioning correctly and requiring expensive visits to fix the problems.

Ofcourse, they will be free to offer the web interface as an addon option, but the option to turn the N800 into a dedicated home automation controller is a huge attraction to the device, amongst its astronishingly low price-point when compared to the prices of current dedicated proprietary automation touch screens.