Manhunt is taking a similar approach to another Rockstar franchise, Grand Theft Auto. In that lead role will change with every new edition. The publisher has a good reason for the casting changeup. Narratively, they want to explore fresh themes.
In Manhunt 2, players can now crawl and the hunters will grab anybody out of the cramped space if they see you enter. and since the player can now climb and vault obstacles, hunters can do the same. Washbrook even promises more enemy tricks that have yet to be revealed, and that "the changes to the the Al have significantly ratcheted up the tension and suspense. Perhaps the bad guys will turn the tables and perform execution too.