Rav Yitchak Cohen from Yeshiva University explained this to me about 40 years ago when I asked him this question as a student in his class.
He said that the purpose of the Gemarah is not to always tell you the answers. It is the questions that are the most important. The purpouse of the Gemarah is Torah Sheb'al Peh - the Oral law. In that sense, it mimicks the written Torah, itself. The written Torah generally does not explicitly state how to do something. One main reason for that technique is to have you delve into it so that you can ask questions and delve further into discovering the answers.
The Gemarah too, presents thing sin a question and answer style and offers various opinions with arguments and proofs and rebuttals. Why not just get to the point and tell you "do this"? Often the Gemarrah doesn't know the answer which is what taiku is. But even if it did give you the final answer, which it frequently does, perhaps, more than you may realize, the purpouse is really to appreciate the discussion and methodology and get you to ask the questions.
In short, Rav Cohen explained, that the questions are far more important than the answers. And, it's also a disciplinary lesson, Rav Cohen explained. It teaches you the discipline of learning to accept unanswered questions in life. (FYI - this is a tough challenge for the average person, but Rav Cohen taught me that learning Gemarrah really does train you in this discipline!)