For me, there are two primary reasons:
A -- The management experience here is much deeper and more realistic than in Madden.
B -- In Madden, if you're good with the controls, you can make most players into HOFamers. Here, they have to (i) fit into the scheme; (ii) know the playbook; (iii) have the physical ability; and (iv) have the mental ability.
Madden sits in the CE box. It seems like a great game on its own, and the presentation is spectacular, but it's just not as interesting as HC.