I could say that you implied it when you said that Vergil wasn't as innovative as Nero, but then you'd ask for more proof, and then it would be an off-topic discussion all over again. Back on to the main topic.
Fine. Then it's NT's fault. I never said it wasn't. NT would have learned nothing then if they want to keep the current combat engine.
Just because I think Nero's combat is very creative and more new than a character that was shoehorned in there in a "special edition" of a version just because of fan demand.
Thought was put into Nero's combat while Vergil was thrown in a "second version" of the same game reusing the same moves and animations he had when he was boss character.
I still like DMC3 more although I enjoy DMC4's combat more but DMC4 does lacks some of the epic stuff of DMC3.
However, your wrong about the whole DMC3 vs DMC4 topic. DMC3 and DMC4 still uses the same type of combat as DMC4 and vice versa the only difference is that in DMC4 is that you can switch styles and switch between 6 weapons instead of 4. The problem with DMC4 on a combat/gameplay level is that it lacks certain moves that made DMC3 despite being able to style switch extremely fun like the enemy surfing, wall running, Wild Stomp, and the charge shots (look better) and the weapons for the most part were just boss. I mean Dante's basic kits in DMC4 (Rebellion, E&I, and the Shot Guns) were better there than in DMC3 but Gilgamesh though nice and I love Kick 13...abuse the sh*t out of that move isn't as awesome as Beowulf's Swordmaster moves. Agni & Rudra, Nevan, and Cerberus were both extremely beastly in moves and usage and even the guns in DMC3 were amazing particular Artemis (once you learned how to use it). Spiral and Kalina Ann had that one move that I loved having Gunslinger equipped to use.
DMC4's combat is no doubt more deep and from a technical standpoint a better version of DMC3's combat but DMC3's combat is more fun and satisfying for all the little things count.