I don’t really think this question has any point. We can’t know, we can only observe and hypothesize
My personal opinion on the subject? God knew that once we reach the point of being able to study it, we would find the history of our world and the species that lived on it endlessly fascinating.
Dinosaurs are awesome, and that it why God took so long; to include these types of species in creation so that we could find them and be in awe of the wonders of creation.
Also, it does a better job of showing God’s power. Sure, you could just pop everything into existence, that it certainly an unbelievable display of God’s abilities. However, in my book it is a greater display of ability, and love/care, to guide a universe over the course of billions of years, to reach the desired state when you actually introduce the life you created it for.
There’s also the fact that time is meaningless to God…
That’s just my take though…