So that's why. Capcom, like so many others, saw the opportunity to get those who skipped the 7th generation councils with the two DMC games that were made in it. I actually think they should consider porting the HD collection, too, because to be honest DMC4 and DmC were pretty low on my list of favorites for the franchise.
I don't know what it would take to port them to the PS4 and XB1 but if they sold the games on their networks for $10 people would most definitely buy the games; if they wanted to add improvements or mods, like style switching for 3 and rebalancing for 2 and another fresh coat of paint for all 3 (like new, higher polygon models) even $20 to $30 would be a decent asking price. But that's just me, though.