Unfortunately with WiFi ‘it is how it is’. Most of the time I get a good (albeit slow) connection, but a few months ago I was informed (via the IFE, I think) that there would be no WiFi at all on a flight (cannot remember the route). I would never depend on WiFi availability on an Emirates flight (and probably not on any flight at all).
The airline clearly states on the website that WiFi cannot be guaranteed. I can understand your disappointment about the availability but it is certainly not a reason to throw miles at everyone who complains.