Reasons are aplenty:
a) Raajneeti has made a statement loud and clear that Ranbir isn't made just for candyfloss cinema. He has the range and if Wake Up Sid and Rocket Singh - Salesman of the Year were the starting points, Raajneeti has been a definite milestone in his career as far as working in offbeat cinema (if looked at from the perspective of what is expected from a young actor of his age) is concerned.
b) The entire balancing act is certainly going in his favour. Just after Wake Up Sid, Ranbir Kapoor returned with a major money spinner in the form of Ajab Prem Ki Ghazab Kahani. While it was always meant to be a so called 'safe film' (in Bollywood parlance), the fact remains that it was Ranbir's charm (amongst some genuine comic moments, super hit music and Katrina Kaif's continued luck) which helped it enjoy a long run at the box office.
c) With good critical acclaim as well as commercial success coming his way, Ranbir is pretty much being looked at as a package deal, something which has been nurtured to the fullest in Raajneeti. While his restrained performance has made everyone sit up and take notice of his inherent talent, the roaring box office success has proved that audience are willing to accept him even in those roles where he is not just a chocolate hero.
These are the factors that make Anjaana Anjaani an interesting case study on what to expect from Ranbir. He got an initial jolt after Saawariya, only to get a shot in the arm courtesy Bachna Ae Haseeno which had turned out to be a decent success. With Siddharth Anand as the filmmaker who gave Ranbir his first success, Anjaana Anjaani could well be life coming full circle for the director-actor 'jodi'.
Says a veteran industry follower, "The going couldn't have been better for Ranbir as he seems to have planned it all quite well. Soon after a rather serious Raajneeti, he is looking at a young entertainer like Anjaana Anjaani. Then there are films with directors like Imtiaz Ali (Rockstar) and Anurag Basu (Silence). Though it is a common saying that one can't plan things to perfection, especially in the unpredictable world of Bollywood, this is pretty much the case if one looks at the way Ranbir has gone about picking and choosing his projects."