I know schematically The Great pyramid of Giza may not be a typical pyramid but it still fits in the realm of a pyramid. It was created during the same time frame as the other pyramids and should be considered a part of those great architecture marvels. The pyramids are all still great wonders of the world .
The great pyramid of Giza has held its name for hundreds of years and is recorded in numerous history books, textbooks, and academic papers. Changing its name based on semantics would require a thorough editing of not only the physical texts containing references to the pyramid, but an alteration and tweaking of a massive amount of search engine results and online articles. It would confuse people and likely cause tourism rates to drop, as evidence suggests the general populace does not react positively to the renaming of famous monuments, resulting in a loss of revenue and a rise in aggravation. Even though a name change might make sense from a practical and technical standpoint, it would be a logistical nightmare and do more harm than good.
A pyramid is a pyramid, and whether it has three sides, four sides, eight sides or twenty sides, it is still a pyramid. If it has a base and it all meets at a single point at the top, then it is a pyramid. Let's not be making a big deal out of a non-issue.
It's been called the Great Pyramid of Giza for years. If you suddenly changed the name, people wouldn't know what you were talking about. "The Great Octagon of Giza" would just confuse people. It's okay to hold onto some things for tradition's sake if they are not hurting anyone, and calling this a pyramid, even though it is not one, is not hurting anyone.