God gave the Jewish people signs and wonders, yet they still did not believe in Him. Consider, for example, them making a golden calf not long after being miraculously delivered from the pharaohs' grasp in the land of Egypt. In fact, their lengthy record of unfaithfulness as narrated in the Old Testament gives witness to this point.
The Jews did not accept Christ even though He performed miracles (Matthew 12:39; 16:4), which were verifiable to their senses. There was nothing concealed about the ministry of Christ (1 John 1:1-4). Therefore, the problem with mankind is not evidential, but his sinful heart. Advances in learning have not helped him to grow out of rebelling against his Maker.
God has revealed Himself to us. He has given to us special revelation (Luke 16:29-31). He has revealed Himself to us through creation (Romans 1:20). He has revealed Himself to us through the person of Jesus Christ (Hebrews 1:1-3). He speaks to us daily through the Holy Scriptures. God has spoken to man in various ways.
God has not manifested Himself directly to human beings throughout most of history. Practically every person of faith has not had such an encounter with Him while alive on this earth. What makes us so special that we should be treated any differently? Hence, we should not be surprised or shocked that God does not speak audibly to us right now.
The Bible as a whole documents roughly 200 miracles. That is not a large number given it was written over the course of thousands of years. How things take place right now concerning the occurrence of miracles is consistent with history in its entirety. It is almost certain that the vast majority of people will never see a miraculous event happen during their lives.
If miracles happened on a regular basis, then they would cease to be miraculous. They could no longer be used for the specific purposes that God ordains. Miracles would be ordinary events, just like driving or washing the dishes. They would no longer stand out to us as different.
The question should not so much be why God does not reveal Himself to us in a more obvious way, but when is enough evidence enough? There are people who would not be satisfied, even if He spoke audibly to them or brought someone back from the dead.