Resigning like this is unprecedented. Popes have been imprisoned and murdered and don’t abandon their flock.
Wrong.
Pope St. Pontian, in 235, one of the first bishops of Rome, who was arrested and sent to the salt mines, and in order for a successor to be able to be elected in Rome, he resigned his office.
Pope Benedict IX, in the 1040s, resigned and attempted to re-acquire the papacy several times.
Pope Celestine V resigned after a shor time in the See, and Gregory XIII resigned as well.
It doesn't happen often but it has happened.
From Wikipedia: The Catholic Encyclopedia notes the historically obscure resignations of Pope Pontian[6] (230–235) and Pope Marcellinus (296–308), the historically postulated resignation of Pope Liberius (352–366),[3] and that one (unspecified) catalogue of popes lists Pope John XVIII as resigning office in 1009 and ending his life as a monk.[7][8] The first historically unquestionable[3] Papal resignation is that of Pope Benedict IX in 1045. In order to rid the Church of the scandalous Benedict, Pope Gregory VI gave Benedict "valuable possessions"[3] to resign the papacy in his favour.[9] Gregory himself resigned in 1046 because the arrangement he had entered into with Benedict was considered simony. A well-known resignation of a Pope is that of Pope Celestine V in 1294. After only five months of pontificate, he issued a solemn decree declaring it permissible for a Pope to resign, and then did so himself. He lived two more years as a hermit and then prisoner of his successor Pope Boniface VIII and was later canonised. Celestine's decree, and that of Boniface concurring, ended any doubt among canonists about the possibility of a valid Papal resignation.[10] Pope Gregory XII (1406–1415) resigned in 1415 in order to end the Western Schism, which had reached the point where there were three claimants to the Papal throne: Roman Pope Gregory XII, Avignon Antipope Benedict XIII, and Pisan Antipope John XXIII. Before resigning he formally convened the already existing Council of Constance and authorized it to elect his successor. There were als several "Conditional" resignations: Before setting out for Paris to crown Napoleon in 1804, Pope Pius VII (1800–1823) signed a document of resignation to take effect if he were imprisoned in France.[3] It has been claimed that during World War II, Pius XII drew up a document with instructions that, if he were kidnapped by the Nazis, he was to be considered to have resigned his office, and that the College of Cardinals were to evacuate to neutral Portugal and elect a successor.[11] In February 1989 Pope John Paul II wrote a letter of resignation to the Dean of the College of Cardinals, which said that he would resign from the papacy in one of two cases: if he had an incurable disease that would prevent him from exercising the apostolic ministry; or in case of a "severe and prolonged impairment" that would have kept him from being the pope.
No it is not unprecedented. Pope’s have resigned as you know. I frankly find it refreshing that he steps down as he finds himself deteriorating and unable to perform at an acceptable level. He is 85 years old and not in great health.
Pope Benedict isn't abandoning anyone. He gave plenty of notice for the College of Cardinals to have time to meet and choose a successor.
The resignation of a Pope isn't unprecedented; it has happened before, just not for a long time. No reason why they can't, but as Pope Benedict has done, they should be responsible to make sure a successor is chosen.