because of the new concept of device variables it is not possible to add more then one channel to a device. The reason is that, if a device driver has more then one channel, from which channel do we fill the device variables? The device variables represent the current state of the device.
In your 72 Projectors example, if we have one device with 72 channels, how can a device variable represent the selected input, lamp hours or power status of all those projectors?
Also in V-Control 4, channels should not block any more. Now all the commands that have to be sent to a device are written in a list. Every 10 ms the list is processed and all commands in the list are fired. If the list contains 2 commands for one device, then the last command is executed. If the second command is a monitor command(which fires periodically) the command will be removed from the list. If it is not a monitor command, then the command will not send (because we wait for the acknowledge of the first command), but will be fired as soon as the acknowledge of the firs command is processed.