An interview from Japan translated by a member of the www.neogaf.com forums---
Note: This is a summary not direct translation
What's the plan for DMC4?
-The big theme is "Next-gen aka. NEW", we've been trying all sorts of new ideas, and there's a 'new' lead.
-A few reasons. For one Dante has this aura associated around him of being in HARD games. As the PS3 is a new machine, it will have a new audience, many who haven't played DMC before, and we don't want to scare them off thinking it'll be too hard and not giving it a chance. Also since the users will be new to the DMC universe we wanted to give them a character that is new as well, so when the character meets Dante for the first time, new players will be meeting him for the first time as well. Now old fans will still get a kick out of it, seeing "oh this is how Dante acts in these situations!". Also we really couldn't implement the arm (Devil Bringer) concept with Dante. Sure we could've figured out some way to give it to him, but even if Dante had the Devil Bringer, going by his personality he'd still kick the **** out of everything with his guns and sword; he has no need for another attacking style. Finally Dante at the end of DMC3 is really powerful after the players have gotten all his abilities. Now we could zap all his powers away and start him from scratch, but that's lame. The other way around this is that we could have set DMC4 even BEFORE DMC3 where Dante is just a newbie but then he'd have to have less attacks/abilities than DMC3 and going a step back would be no fun for the player.
-(blah blah blah he can use it as a 3rd way of attacking blah blah blah). As designers with Dante only being able to use the sword and guns, it sorta limited us in our enemy/boss designs since we had to design them around those two attacks. We couldn't make any cool fights that would require players to attack with a different method. With Nero's ability to grab and throw, we can think up all kinds of cool situations and strategies that would be fresh and fun. [probaby like throwing dudes into spiked walls or something?]. So not only does it give the players more options, it gives us more options in designing the enemy patterns, which is always a plus.
-DMC4 is a game that can only be made with the power of the Playstation 3 (blah blah blah next-gen machines rock blah blah blah). One thing that's cool about having the power of the PS3 is that instead of just doing dark night stuff or foggy stuff, we can do awesome looking blue skies and even the sea and do it with awesome graphics. We're gonna have locations in DMC4 that will make the players go "WTF!? Is this really a DMC game?" [lol, boat stage confirmed :P]. We want the locations and visual and ambience to be a 'new' experience and only the power of the Playstation 3 can bring that.
-We want to make a game that has the impact on the PS3 and gaming world that DMC1 had on the PS2.
-Also we've worked really hard on the movement and animation of the main character. In a lot of action games, the difficulty is actually because the charactere control's badly or the animations are too long and un-interruptable, we've worked really hard as a base to make the movement and animations great, so we hope everyone enjoys it.
Last words to the fans?
-The TGS demo was just a drop in the bucket, I can say with confidence that we're making a game that will make you say "I'm really glad I bought a Playstation 3". We're not going to let you down. We're making a game that has tons of depth and replayability to it that'll keep you satisfied.