1315trinity:
I think the issue is that in years gone by, many more neutrals went to the Wembley final because it's was a big sporting event, even out of RL.
Unfortunately it isn't now, and there are many more attractions for people nowadays so we have to accept that.
I personally feel Wembley is just a hike too far and the final would be a better occasion if it was held in the area RL is played.
You've also got Magic Weekend, trip to Catalans and (sometimes) end of year Internationals to think about. Just going to a single Superleague game isn't exactly cheap, either.
Factor in family summer holidays, Christmas etc etc there's not much brass int pocket.