If the game is to be set after DMC1 or DMC2, then for continuity, it wouldn't make much sense for him to be like he was in DMC3. However, I thought he kicked more ass in DMC3. He wasn't just a clown the whole time, he just did loads of ridiculous over-the-top unnecessarily stylish stuff and had some wise-cracks. But he was also serious at some points, I think they had it just right so he did have some genuine emotion like at the end, and had serious anger towards Vergil at times too, like in the cut scenes of his fight(s) with Vergil, it's not like he was laughing and saying 'hey vergil you smell like poopie' in the most dramatic parts.