OK, that may be a bit harsh. But the danger is that a translation that is out-of-date or badly done will turn you off the book. Many classic books whose translations are now beyond copyright are available for free. But these translations are, generally speaking, poor. To really appreciate these books, find a translation that is up-to-date and that suits your reading style.
I think that's an unfair characterization - Benjamin Jowett's translations of Plato's dialogues are decent and readable (these are readily available online). I also liked H.G. Dakyn's translations of Xenophon's The Memorabilia and The Symposium:
https://www.gutenberg.org/cache/epub/1177/pg1177-images.html
https://www.gutenberg.org/cache/epub/1181/pg1181-images.html