Not me, I avoid LGW at all costs. LGW is basically London B class airport. Just As Westjet avoids YYZ at the start, they will end up in LHR.
The economic case for making that move would probably see the business traveller shoulder all that cost. As about 90% of people on WestJet flights are not business orientated or price insensitive, they are shopping mainly on price, so whether the destination is LGW or LHR, the ticket price will need to be the same to remain competitive. This means the amortized slot costs of about $80 per return ticket will be need to be borne by the 10%, likely to the tune of about $1000 higher business class ticket price for LHR vs LGW and $200 per premium economy ticket, keeping the Econo and Basic tickets at the same price.