This is an important point about a lot of sophisticated models; you're really fighting for a few percent improvement over simple approaches. Sometimes a basic

This is an important point about a lot of sophisticated models; you're really fighting for a few percent improvement over simple approaches. Sometimes a basic linear regression will get you 70% there, while a trained neural net will bring that up to... 75%. A few percent can make a difference, especially in competitive areas; but the biggest win is just getting something in where there was nothing before. It's a bit like optimizing code.