I don't know if Madden is that much of a 'niche title' - it's very aggressively advertised on TV and via social media. But maybe that's how the Madden demographic is reached, and really this is not a major point.
My first post in this thread pointed out that Madden is one of EA's better games, but it still isn't very good, largely due to the lack of innovation that you point out. This is part of EA's problem though - even its best titles aren't generating enough good will to counter the bad. When people get burned by Sim City or feel nickel-and-dimed by DLC in Dead Space 3 or whatever, they don't have that really good game that makes them say, "Nah, EA isn't the worst."