...because chances are that the slow peace will only appeal to few people. It's also not a show you could just hop in to mid-season, so again, the ratings may suffer for that reason alone.
I really love the actors, great casting all around I think. Excellent story, love the real life "cloak-and-dagger" setting without the explosions etc. But I'm positively scared to get invested into the show, because chances are we'll end up with a cliffhanger and no second season. That seems to be the fate of these kind of shows lately (for years). I'll keep my fingers crossed.