Whereas Morrowind will happily run all of them loaded at once, in total there is roughly 350mb of plugins. The biggest being Cyrodil
EDIT: Keep the questions and comments coming
Id recommend, for testing purposes, using yacobys mesh generator to place statics all over and then putting it into Morrowind n seeing how well morrowind runs it. And to find out of the "if you are so far from 0,0 everything shakes" rumor is true, as Ive yet to see anybody reproduce that result.