People play for fun and amusement, but you've taken that out of the equation.
That may be the case for you but, and I can only speak for myself here, I'm still playing the game and enjoying it as much as I ever did. I'd be fairly certain there are plenty of others in the same boat.
At the moment, I imagine most of their efforts, like a lot of companies I've worked with/for, are going into the continued development and debugging of the PCEA version of the game because of the upcoming death of flash.
As for their marketing, up until recently I'd never seen any adverts for WGT anywhere online but I now get them regularly on google ads - I'm sure they'll have gained some new members through people clicking through on them and starting to play the game. That suggests that their marketing manager is trying to maintain interest in their game.
Finally - I'm not sure where you get your figures from, but suggesting some incentives would've generated 5 times their normal revenue sounds like pie in the sky to me.