Bridges are actually not so bad imo
Why /not/ have a separate control device for different categories of systems? As it is, I see separate controllers for Internet access, Wifi provisions, lighting, HVAC, TV, telephony, fire and regular alarms, cctv, door security etc. and it is not the worst way to handle separate tasks.
Network bridges have been around for a long time, and they are generally useful middle-hardware that makes it easier to maintain both sides of the bridge, without having to make sure each side is exactly compatible with the other. So yeah, by all means put different home automation systems behind separate bridge/controller devices. Easier to maintain, easier to secure, less devastating when it fails. Unless of course you like Scala and the associated risk of taking out all infrastructure when a single device goes down.