I used to think that if there are no options but to go to work when it rains/gloomy.
But look at the flip side, for a city that is well-known for 10 months of gloominess could be easily one of the reasons why people are not coming here or trying to leave. This minimize the talent pool however you read the situation.
Seattle, while having similar weather, has the advantage of being a "US" states. USA as a brand is huge. Given Vancouver vs Seattle, people would choose the latter quicker than the former. Hence there are more people in Seattle compare to Vancouver.
BC's economy is mainly service-driven because what else can they do with the lack of demand?