Why aren't these censored pieces of Torah added back in to all editions, now that we know of them? Are there any published editions of the Talmud that still contain the authentic, unadulterated texts, (as far as we know them)?
These changes have been known for some time, and many were published in books such as "Chesronos HaShas". However, everyone is already so used to the folio-daf system in the Vilna (Bomberg/Romm) edition that everyone uses those pages for a reference, and we wouldn't want to confuse everyone by having to re-paginate the Gemaras. Basically, the reason is merely that the Jewish people is an ancient people who don't like changing things. Is that a great reason? No, but that's how things are.
The Koren-Steinsaltz Gemaras that are being published in Hebrew contain these missing parts, and their Hebrew counterparts (the Hebrew Steinsaltz Gemaras) have added these censored passages.
The Moznayim, i.e. Vagshal prints have all the censored pieces put back, also of interest is Dikdukei Sofrim which has at least 4 ancient manuscripts predating the printing press standardised shaas. The reason not to put them back is because the Jews in Spain, Poland, Germany and countless other countries taught us a valuable lesson with their lives that no matter how good galus (exile) seems, it's still galus. I've actually read an antisemitic blog quoting translations of gemaras, mostly from Lubavitch websites, citing various censored pieces about Yashka, calling on his antisemite brothers to wake up about the truth of our feelings to their deity. He went on to mock us for foolishly thinking we are safe enough to print these things publicly. Very surreal.