A very interesting question. I would say yes and no.
Yes, because of what you mentioned: vocabulary and grammar.
No, because texts written in dead languages usually refer to old cultures, whereas words and phrases could be quite challenging to translate accurately, so that present day's readers get it. Alone the fact that some text can be a thousand years old makes it hard to understand. Look at some parts of the Bible for example. Even Christian priests and preachers struggle with explaining it, because of the use of words.