Differences in getIP() syntax

FYI, getIP on the esp8266 also accepts a callback function, so if you want to write portable code you can stick to the async callback:

wifi.getIP(function(x){console.log("got", x);})
={
  "ip": "192.168.0.197",
  "netmask": "255.255.255.0",
  "gw": "192.168.0.1",
  "mac": "5c:cf:7f:10:a2:42"
 }
got {
  "ip": "192.168.0.197",
  "netmask": "255.255.255.0",
  "gw": "192.168.0.1",
  "mac": "5c:cf:7f:10:a2:42"
 }

Collectively we spent days discussing Wifi for ESP8266, and made a
huge wiki page where we agreed on an API that would work for both.

Ultimately it got totally ignored when ESP8266 was implemented though,
and sadly it's stuck since I have no time to fix it :)

I'm not sure why you feel this way. Some of the stuff specified on that page didn't work or didn't mesh with reality. I tried to stick to it, but some of it neither made sense nor was it consistent.