I'm not a religious scholar, nor am I going to claim to be one. I'm not super well versed into Biblical lore, either, but if you want to try and discount the Book of Revelation, you create structural issues in the Bible. Jesus is supposed to be the Messiah, and while he meets most requirements, the question of "Why hasn't the Messianic age been issued to us?" raises issues with a "Just the gospels" take like yours.

Just to be clear, the Messianic age is supposed to be an era of global peace, lasting up to a millennia in some thoughts. There has been 0 continuous period of global peace since the first coming of Jesus to the world. This creates a few possibilities, either that Jesus is supposed to come again at some point in time, to fulfill the Messianic prophecies, that Jesus isn't the Messiah but still is supposed to be the Son of God, which starts to contradict itself, since Jesus is given titles like "Lord of the Sabbath", or "Christ", both being references back to claiming the status of Messiah, or that the original prophecies of the Messiah are bunk, which wouldn't make a lot of sense, either, since Jesus himself refers back to those writings.

The only thing that would resemble a self-consistent writing requires the return of Jesus to fulfill the last few parts of the Messianic prophecies, and that's where the Book of Revelation fits in. To my knowledge, there is no other writing, Book, or apocrypha that foretells of Jesus's 2nd coming in a way that explicitly rules out Revelation as happening, while one can draw obvious parallels to a number of the Seals spoken of in Revelation 6 in current events.