Rugby League is unlike football, for example, in that friendlies don't really exist. Football has become a non contact sport and as such friendlies are a good chance to try out combinations with not much chance of injury. However in RL the players risk injury every time they cross the 'whitewash' (channelling Stevo!).
We are playing a glorified 'friendly' against the Rabbitohs in February in any case after just two league games. I will be at Leigh but I'd be gutted if Sam Tomkins or Sean O'Loughlin got an injury that kept them out for the season. No sense in risking them. The season is plenty long enough and you don't need to hit top form until April/May time anyway. Leeds have this down to a fine art, I could be wrong but I don't think they have won the LLS in any of their GF winning seasons (I can't be bothered checking tbh)
It should be a game for fringe players, the likes of Isa, Marshall, Forsyth, Sutton, Higginson, Shorrocks, Wells and so on.