Can an emotional letter of motivation be harmful in a PhD application?
In brief, even after imagining that text's language cleaned up, the problem is not about "emotion" but about lack of verifiable substance. As in @aesmail's good answer, insubstantiated claims, or, worse, claims which appear to be counter to any documentable reality, are at best unpersuasive. For example, unsupported claims about the quality of one's university or department are at best pointless, and suggest that one does not know how things work. Proposing to "collect new knowledge" gives a very strange impression, as though the writer believed that learning new things was somehow unusual... while being remarkably inspecific. 

That is, if I were to receive such a letter, I'd consider it basically content-free, for all practical purposes. "Emotion" is not the issue. The problem is that such letters should not be content-free, but should include tangibles, past accomplishments and connections with the future, etc. A content-free letter competes very badly with content-ful letters.