A lot of people don’t understand that being conservative with change doesn’t always mean less errors; it means old problems stick around forever. Net result is the same number of issues. That’s a general response to a specific question, but the principle holds.

Many of those things aren’t “wired” (more accurately, IP networked) because the risks of doing so outweigh the benefits, at least in the “industrial” realm I work in (admittedly more critical/higher consequences than your average building HVAC). Even in the HVAC business, there has to be some incentive; network interfaces, like variable-frequency motor drives, cost money.

And the industrial realm is a conservative place. Vendors have been hawking digital fieldbuses for years, yet 4-20mA current loop still rules. Wireless standards (ISA S100, WirelessHART) have come on the scene, and while they are used in edge cases where wiring is impractical, you don’t see very many people running an entire plant on them. Simplicity and robustness are still paramount.