The issue is, they can't possibly undergo a massive international expansion from Edmonton without compromising another the entire existence of their Calgary "base". Having an expansion from a market that already partly powers their current hub would just lead to them cannibalizing their own services. Air Canada manages to have multiple hubs because they are both larger cities and are further apart. If we're here to critique Westjet's model and not just get sour about YEG's lack of transatlantic flights, YVR would be the better target for expansion.... and I personally believe they will tap into that market again sooner or later.
This is why, as disappointed as I am too, it's extremely naive to get mad at WS for not throwing money at YEG for international flights like some people here (and on other parts of the internet) often do. Edmonton wasn't picked as an international base on the hub-and-spoke model, Calgary was. You can't have both, that will never change.
It just kind of sucks that this thread seems to only ever get active when there's some expansion from Westjet, and everyone is only ever capable of seeing the negatives. It's always just the uninformed griping along the lines of "Westjet sucks and is destined to fail because they chose Calgary over Edmonton".