True. Although, I kinda expect towers to be somewhat upgradeable (that's the whole point of buying them, for many).
But iMacs and Mac minis? THAT'S a new one...Apple might not want their bread-and-butter, "everyman" gear to be quite so "open-ended".
As for "not knowing how to upgrade", this seems pretty easy. A straight drop-in that any person smart enough to buy a Mac to begin with could probably handle?