Exactly. Think of the purpose the inscriptions inside a tomb. Nobody is going to see them, so why bother? The Pyramid Texts mark the beginning of an Egyptian magical tradition where writings and images can help the deceased in the afterlife. This tradition apparently started with Unas in the 5th dynasty and developed into the Coffin Texts, Book of the Dead scrolls, and finally hypocephali at the very end of Pharaonic Egypt.
With Khufu (4th Dynasty, Great Pyramid), the inscriptions are in his mortuary temple right outside the pyramid because that's where people would actually visit, not the interior of the sealed pyramid.