The EJ aircraft are based in LGW. If, say for arguments sake, they launched last night and didn't get in, then they end up with an aircraft out of position for the next days flying. Which, as the aircraft is LGW based, will impact flights from there NOT inverness. So, last night, some Ops guy at EJ took one look at the TAF and decided to cancel the flight. This in their eyes, reduces their exposure to disruption the next day by keeping their aircraft and, importantly, the crew, where they are based. Shortsighted? In hindsight, yes as the RVR never dropped below 700m last night, but the decision was made based on the forecast and you can't blame them for that.
If EJ/BA/Flybe or whoever had a base at INV, then chances are the aircraft will have a full days flying out of INV. So yes, then they would have been more inclined to 'give it a go' as then they are trying to get their aircraft and crew where it is supposed to be.
My point is that these cancellations will be more common over the winter, so get used to it. It's nothing to do with the equipment or the crews that fly them.