I think it is fine as a SP only release. Future work on the project should be focusing on fixing bugs and balancing the game. But that's just my opinion.
It might be simple to add in multiplayer and co-op but there is already another MoW expansion in development which will be focusing on co-op and MP. People often forget this.
If Red Tide had everything the old MoW had, then people would be unable to play both games, because well, what would be the point?
If Red Tide also had MP then the majority of the people who are currently playing the original MP (those who have bought Red Tide) would probably move on to that. Which could lower the # of people around to play the original, which would eventually result in the game dying.
No point in splitting the community in two.
I can see the attraction to MP/Co-op in these games, but remember we already have 1 game that does both, and another one coming..Is one SP-only title really so bad?
Though i will admit i wouldn't say no to a patch/update which allows co-op play, that's always a blast.
