I just noticed something really weird regarding the Forest Temples placement in regards to Hyrule Castle (OOT). Have a look at the maps of Hyrule from Alttp and Oot. Look at where the castles and forests are, there are some really cool connections.
First, if we could only pretend for a moment that Alttp could come before Oot in the timeline. This way, the forest temple could be the ruins of Alttp's Hyrule castle. So this means that hey would have needed to build a new hyrule castle and what better place to build it than right near the blade of evils bane.
I dunno this is just one thing that came into my mind, totally imaginative but if someone else can see anything here, I'm sure there's something I'm missing.