i guess it has to be asked what you actually mean by saying it's no longer a "simple hobby..."
i mean first of all it's just as much a simple hobby as any other medium of entertainment, like television or books, and if you're saying people getting caught up in ARGs or the lore of a work is indicative of gaming becoming a less-casual space, that's frankly fairly silly; it's simply another way in which people can enjoy the games they like by participating in a larger continuity or overarching experience external to the game itself
in addition i would have to question the idea that that development is actually a bad thing
i might just be misunderstanding here but