Royal Blood are a relatively new band, and they have not yet achieved the level of fame and success that would warrant them being able to demand a certain level of energy and enthusiasm from their audience.
Even if the audience was not as energetic as Royal Blood would have liked, there is no excuse for Kerr's behavior. He was rude and disrespectful to the audience, and he showed a complete lack of professionalism.
Kerr's behavior is a reflection of his own entitlement. He seems to believe that he is owed a certain level of respect and attention, regardless of the circumstances.
Good audiences need to be earned. They are not something that can be demanded. Bands need to work hard to connect with their audience and to earn their respect.