I think you’re not far off. I saw a great book a while back, I believe it may have been “A Travel Guide to Heaven” or something similar. It basically said, “maybe God made the dinosaurs so that 300 million years later little children would look at their bones in museums and be amazed.” That’s good enough for me.
I’m also a reminded of the closing lines from War of the Worlds. I’m paraphrasing a bit, but the line is that “in the end, mankind was saved, after all his weapons had failed him, by the tiniest of creatures, bacteria, which God, in His infinite wisdom, had seen fit to place upon the earth.”
…and so it is with the dinosaurs. We don’t really know the reason, but whatever it was, it was a great one.