Why Moria?

[Inziladun]

Originally Posted by Rhod the Red

It would have been great if Tolkien had Radagast helped them through Moria or something like that and escorts them to Lorien and then heads north back to his home, etc.

But that might have required substantial changes to the storyline. Though I wouldn't have been opposed to that, anything to give other wizards than just Gandalf parts in TLotR.

What's wrong with Gandalf being the guide? Not only was he the de facto leader of the Fellowship, he'd been through Moria once before.
Also, he had been the prime mover of the resistance to Sauron, since Saruman had effectively abdicated his responsibilities of on that score. Moving Radagast more to the forefront would indeed have required some notable changes, and I for one don't see the benefit of it.