To prevent your question being closed down (for not being 'aimed' at a particular group within Christianity), I am going to answer as one who believes that God does, indeed, communicate in certain ways today, though such ways are largely different to the instances you refer to, in the distant past.
I can see how your main question is linked with your secondary, final question, though someone has suggested you remove that last question and post it separately. So, I will start at the beginning of your post, and see how far that can go.
First part of my answer: The Old Testament does have a great many examples of God miraculously intervening on behalf of his people, or of warning them when they continued to disobey, so that when his divine punishments came, they would know it was just as surely him acting, as when he acted to bless them.
However, even a cursory reading of the O.T. must take the huge time-line into account, and also the tiny size of the people of God who experienced his intermittent miracles. This reveals that there could be, say, 40 year's gap in miracles, or even hundreds of years' gap.
Take the generation that directly witnessed the ten plagues on Egypt so that God liberated them, then experienced the further miracles of the pillars of cloud and fire, the parting of the Red Sea with the destruction of the Egyptian army pursuing them. They also witnessed the awesome near-presence of God on Mount Sinai. A huge spate of miracles in a very short space of time! Ah, but shortly after, the people began to grumble against God, resented the food and water he miraculously provided, then disobeyed when the time came to enter the Promised Land. Only two out of ten spies urged them to go ahead; they heeded the eight. Therefore, God punished that whole generation by sending them back into the wilderness for 40 years, so that that generation would die off there, never getting into the Promised Land. (Read Numbers chapters 1:1-4 and 26:1-4 & 61-65.) Their descendants did.
Yet even in their punishment, that faithless generation experienced the miracle of their footwear and clothes never wearing out. Their children would no doubt remember that.
Second part of my answer: Fast-forward to God's punishment on his people, with the third deportation to Babylon in 586 B.C. The only people (captive in Babylon) who heard God speak, and witnessed miracles, were the likes of Daniel, Shadrach, Meshach and Abednego. Other prophets wrote what God told them, but from the end of the 'minor' prophets till the miracle of Jesus being born was around 400 years. There is a huge time-gap in scripture where the heavens were as brass.
Both parts put together: God rarely speaks or performs miracles. It is a mistake to read about such biblical events without noting the huge time gaps and how tiny the group of people were who witnessed them. Sometimes, only individuals did. But because the Holy Spirit caused written records to be made, copied, preserved and handed down through the centuries to God's people, we can read all about them. So, it might seem at first glance that God's voice and his miracles abounded when, in fact, even bouts of such divine activity were rare events, and many witnesses soon forgot and reverted back to unbelief, which always leads to ungodly living.
Conclusion: Don't assume that God does not appear to speak to his people outside of the Bible's accounts of miracles. You can only speak for yourself. You have no idea how many miracles and messages God conveyed to faithful believers throughout the centuries after the last book of the Bible had been written - and which he continues to do today, to those with ears to hear and eyes to see, that is.
After Jesus miraculously returned to heaven, the Holy Spirit was sent to indwell every believer, to teach, guide, encourage and assure. The Church Jesus started, which (he promised) the very gates of Hades would never overcome, continues to grow miraculously. Faithful preachers of the biblical gospel risk life, limb and everything to further the interests of the Kingdom of God, as they seek his righteousness (Mt. 6:33). Sometimes they experience a direct 'word' of direction, or a miraculous event. Sometimes not. The full number of the martyrs must be reached before God acts to bring vengeance on their killers (Rev. 6:9-11). And, throughout, God's people have his written word. But if they'd don't heed that, they need not expect a word, or an action, of favour to them, personally.
So, is your mind and heart open to the fullness of how God deals with his people? His arm is not shortened, that it cannot save; the Lord knows those who are his; not one person given to Jesus to be saved will be lost. The promises are still there. Do we believe them and act in faith? If so, then we will hear and see how God communicates with his faithful believers today.