Nah, they're just making enough product so they can get their own fix, too. Did you ever follow the competitive scene? I swear that's what really got me into it. My only peeve is there's no real sense of fan loyalty since all teams are based in the same area, meaning bandwagonning is where the masses thrall to. Other than that, it only serves the hype. Their promo team is fire. They out-sourced this piece: Most promo clips are outsourced, from what I read. Even some modeling of champions, IIRC. The thing that tickles me is the studio which created the piece shown is Studio Mir (which did AtLA and LoK).
I would definitely watch streams, but not to follow the pros as much as to gain insight as to how to get better. But you're right, Riot is on their shit with the marketplace and all the goodies just a click away.