A proprietary mesh isn't a problem at all if you're using a Z-Wave (or whatever) to WiFi (or ethernet more likely) gateway to interface with your TCP/IP network. I don't think having every light switch on your LAN will be very good in practice. I'd much rather have a single controller able to address all the switches, with only that controller connected directly to the LAN. IMO, that's much more useful and would allow a single server-like app to interface with all the switches. Otherwise for that kind of functionality you'd still have to install such software on a server somewhere, also connected to the LAN.