A gute voch. I was wondering why the Hashmonaim did not appoint a descendant of Dovid Hamelech to be king. Surely they knew all the pertinent halachos of kingship and realized that they would incur punishment for setting up a kingdom that was not from Bais Dovid. Thanks.
David Goldman, USA
Hello there and thanks for your interesting question. First let me apologize for not responding earlier. I was away on summer vacation, and fell ill shortly after.
Let me begin by saying that it is never easy to judge Gedolei Olam, especially the Chashmona'im who put their lives on the line for the sake of Torah and Klal Yisrael. The Ramban states that without them, surely Torah would have been forgotten. Rav Yaakov Kaminetzky ZT"L (Emes l"Ya'akov Parshas va'Yechi) explains that the contemporary Gedolei Torah chose not to appoint a monarch from the descendants of David ha'Melech. The reason was that they knew that the Second Beis ha'Mikdash was not meant to last for eternity and the return to Eretz Yisrael from Bavel was a temporary reprieve from Galus. Appointing a king from the Davidic dynasty, would lead to a false impression that this was the ultimate Ge'ulah. This created a leadership vacuum, something which the Chashmona'im fell into. He also points out (based on the Book of the Macabees) that at first they did not refer to themselves as kings, but rather "Nasi". They took this title reluctantly until prophecy will return to the Jewish People. Only in the days of Yanai does the term "king" begin to appear. As we know from the Gemara Kidushin (66a), Yanai was not the most righteous person.
A totally different approach is taken by the Derashos Ran. I will do injustice to him by just quoting his idea in brief. He explains that according to the Gemara in Avodah Zarah (8b, 9a), the Chashmona'i Kingdom was actually a vassal kingdom of Rome. Since it was not real independence, the Chashmona'im were not really kings. Perhaps this approach also answers your question.
May we be zocheh to speedily see the ultimate Ge'ulah led by Mashiach Tzidkeinu.