I would say they are. Unless someone out there has a GPS that spawns pillars of cloud and fire.
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I'm just kidding. Anyway, here is my opinion for what its worth (probably not much). Lets start with Scripture:
1 Long ago, at many times and in many ways, God spoke to our fathers by the prophets, 2 but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. 3 He is the radiance of the glory of God and the exact imprint of his nature, and he upholds the universe by the word of his power. After making purification for sins, he sat down at the right hand of the Majesty on high.
The Holy Bible: English Standard Version. (2016). (Heb 1:1–3). Wheaton, IL: Crossway Bibles.
God has always interacted with His creation whether by direct intervention, divine providence, the prophets, His only Son and the sending forth of His Holy Spirit. Sometimes God works in simple ways perhaps in just one person and at other times in drastic ways. It is my belief that God acted in such a way as to separate out His people. To be the source of Justice and Mercy among his people. When you read the Law you will find the phrase, "As I have delivered you out of Egypt" over and over again. The text will also appeal to those who witnessed these mighty acts. And why did God do such a thing? Because through these people the Messiah, the Christ would be incarnated. Remember, always read the OT through the lens of the NT. You should be able to find Jesus on every page of Scripture.
So why does God work in signs and wonders sometimes and by other means in other times? He works in my opinion in signs and wonders in order to spread the Gospel. Now, you may not think of the giving of the Law on Sinai as Gospel but in a sense it is. Consider, how could sins be forgiven before the giving of the Law? Now the Israelites have a means to be forgiven. It is not a perfect system because the people still had to approach the altar year after year to atone for their sins. The perfection comes with the coming of Jesus. Read Hebrews 8.
And after the coming of Jesus and the announcement of the Good News (Gospel), what accompanied this announcement? Signs and wonders. The sick being healed, the dead being raised, sins forgiven. Now that we have a record of these in the pages of Scripture, the signs and wonders have largley ceased. I say largely because there are stories of signs and wonders in parts of the world where the Scripture is hard to come by or outright illegal. For example I am aware of a christian minister who works in the Middle East among a majority Muslim population who receives visitors all the time stating they had a dream about Jesus or Jesus appeared to them. And not just one time but sometimes over a period of time. And these are not superstitious folks but Engineers, doctors, highly educated folk and common folk. Add to the most of them are muslim in name only so they are not really religious when these events happen to them.
So what'a the bottom line? You are correct. These events are in the Bible because they are kind of a big deal. Also, these supernatural events often announce the intentions of God and his Gospel whether OT or NT.