On the Nero and Dante debate - both characters have potential for growth. Every character ever thought up does. So Nero cried out for Kyrie more times than was necessary, and he actually cried at one point because...well geeze, he was kinda trapped in some ugly bastard's heart and couldn't get out fast enough and he was frustrated that he was where he was because he wasn't able to prevent his capture. I'd be friggin crying too, y'know. That doesn't make him any less than Dante. The same thing about him being younger - younger usually equates to raw strength, which can be daunting. If Nero had had the experience Dante had when facing him in that battle, yeah he would have totally owned Dante's ass. The point is, he didn't have that experience, even after being part of the Order and fighting demons for x amount of years, he still wasn't good enough to pawn Dante. That's where Nero falls short, and that's why Nero wouldn't be fit to be cast as the main character. I can't see him running a devil hunting business - that would put Kyrie at risk, because he'd be pulled into these demonic dealings ALL the time because it's his job. If he was to make a name for himself like Dante, it would be even all the more reason not to have a loved one at all. I always thought that's why Dante was flying solo, because he didn't want anyone close to him to get hurt because of what he does and who he is.
Anyway!
Should Dante come back in the series? YES! Why? There's way too much of his story that we don't know yet, that's all guess work by fans.
Should the series concentrate on Nero? No, not at all. He was introduced into the series as a lonewolf in an Order that was twisted. He saved his girl at the end and he was half demon at the end. Yeah his story could continue, but I'd leave that continuation up to the fanfictioners.
Dante's role in the series may have become fan service, but you need to keep in mind where Capcom has prevailed and where they have failed. Dante is now seen as fan service because he was a co-player in DMC2 and DMC4. He wasn't the center, and really at the end of the day he didn't have THAT much of a major role to play. BUT, DMC1 and DMC3 focussed on Dante, and in BOTH of those games you can see serious character development take place. Do you see the difference here? Do you see where I'm going with this? The best medicine for the series at this point is to keep Dante in the main spotlight and give his character that chance to redeem itself and grow further. A character is only stale when there is no progress made. DMC1 and 3 showed the potential Dante has and how well the series could become if they keep him as the main character.
All I've really done here is elaborated on my initial 'well because he's the main character!' answer.
Oh. And.
Dante is awesome.