Ok, so I am a roadie but would still love for the mtb season to be included somewhere. Mountain bikers have some awesome races such as Leadville, Trans Alps, Trans Rockies, Cape Epic and many more! So, why not include an mtb career option? Surely from a sales point of view, you would get the mtbers also buying the game and converting to road cycling.. (total world domination etc)
I would love to be able to take a Christoph Sauser and make him and his team mate win the Sani2C race, Cape Epic and and and.. without getting dirty myself (that would just be gross)
Most Cycling fans are into road + others. Hense a road based game is more popular. I'd imagine people have made mods to covert te game to mtb, much as they have for cyclo-cross.
Thats pretty much your only option. Tagging a MTX option onto the game would not increase sales enough to warrent the extra spend.
Dont get me wrong, i'd like to see track and mountain bikes muc more incorporated into te game (there are lots of time trialists especially that only do part road seasons and spend alot of time on track. Converting guys from road to track would be nice as well. MTX is also quite a common track of progression, although i think its more stopping one and starting another.) I just dont see it being economically logical. The track tie up is because Track cycing is pretty popular during the olympics i think. It works better for uninformed viewers.
What Flair said, it's all about economics.
Though I believe Road is the nicest thing to have in a game, Mountain Biking would be a nice addition. Maybe it'll come out one day, if it increases in popularity.