Shakespeare is interested in royal power throughout his history plays. In Richard II, he dramatizes two very different attitudes about kingship. According to Richard II and his followers, kings should inherit the crown from their fathers, and they have a right to rule because they are God's chosen representatives on earth. According to Henry Bolingbroke and his followers, a king's right to rule is a privilege granted to him by his subjects, which means the right to rule depends on whether or not a guy is actually a good leader. Literary critics and historians point out that when Shakespeare was writing Richard II, European ideas about power and monarchy were beginning shift from a religious attitude, like Richard's, to a more secular (non-religious) point of view, like Henry's. The play is a reflection of this change.
Although the play portrays Richard II's loss of the crown to Henry, it never actually chooses sides – instead, Richard II shows us various attitudes toward royal power.
Richard II loses the crown because he thinks God will protect him, even though he's a lousy ruler.