My comment was posted in reply to some people challenging whether the Church needed reform. I thought it would be useful for them to know that it is part of the Church's teaching that the Church needs reform. 

Of course, the quotations from Vatican II have to be set in context. Part of that context was pastoral sensitivity – a felt need to tone down the expression. But the more important part of the context is theological. The quote from Lumen Gentium is in paragraph 8: the previous seven paragraphs have set up the Council's vision of what (or really "who") the Church is. The need for "reform" is a consequence of acknowledging that the Church is the People of God, in other words, the baptised.

The fact that the second quote about "reform" comes in the Decree on Ecumenism confirms that behind this assertion is the foundational vision of the Church as the People of God/the baptised. Why? Because we have to take into account that it is not just Catholics who are baptised ...