Because the reader needs to be able to understand what he/she is talking about.
Leartes and Fortinbras share the same fate as Hamlet, the three of them lost their fathers in unfortunate circumstances. They feel the same kind of grieve of losing a loved one. But each reacts, differently. Their behaviour play a close related trait towards advice and duty, action versus inaction and sanity versus madness. Hamlet and Leartes want to get revenge, while the first is looking forward is getting the throne back and considers the consequences of his actions. Leartes, on the other hand, is blinded by his feelings (madness) and takes belligerent actions without thinking on the consequences.
Hamlet and Fortinbras, want to take revenge both. Whereas Hamlet only seeks to get the throne back and keeps on devating on how and when to take action, Fortinbras wants to clean his family's name and fights in an orderly fashion, with the use of an army.
Although there is not a current paragraph related here. According to the actual meaning of the word, vicissitudes, it is possible to say taht this word means difficulties (mainly related to difficult times), that are going to have possitive consequences. In other words, it is possible to say that it has a possitive and a negative meaning at the same time.
A connotative meaning of a word means that, it is the secondary definition of the word which generally expresses the idea or feeling of the word, aside from its dictionary or literal meaning. The word utopia means an imaginary perfect place. In other words, it is a paradise. The connotative definition of utopia is superior and incomparable happiness.
