Budget maybe. MadWorld was their breakout title, and long enough given they needed to get something out the door. Infinite Space was made with Nude Maker and was plenty long. Then was Bayonetta, their big 360/PS3 blockbuster action game. It was in development for two and a half years.
Vanquish and Anarchy Reigns were still tethered to SEGA. Love both, but I'm not confident SEGA cared as much as they did circa Bayonetta for budget reasons. Revengeance is Konami, and I maintain the belief that Platinum was on a tight schedule to pick up KojiPro's slack, so I can understand the relatively short length (though it makes up for it in VR and unlockables in my opinion).
I don't know their internal workings and I don't pretend to, but because I'm on the internet I'll hazard a guess and say they haven't had a development cycle and budget as meaty as Bayonetta since Bayonetta. I guess we'll have to see how Bayonetta 2 and The Wonderful 101 shape up.