How does adding/omitting lemmatization affect TF-IDF?

Lemmatization has some obvious benefits in TF-IDF, e.g. it decreases the vocabulary size.

What are some other advantages, and what are some disadvantages to lemmatizing in the context of TF-IDF?

For example, past tensed words could be judged as more negative / more likely to occur in negative sentences than present tense. The word hated could be more negative than hates.