If you would like to see a tour de force in the use of repeated notes, have a look at Martha Argerich's performance of Scarlatti's D Minor Sonata:
You will notice that she uses 321321 for the rapid notes. Since the accents fall on the first, third and fifth notes, you will see that a different finger is used for each accented note. As such, she isn't doing this because each finger has a different tone quality--it's safe to assume that she doesn't want the tone quality to vary on each note. (Tone quality differences are more noticeable in slower, more melodic passages.) Rather, it's because she can play the notes a lot faster with three fingers than one. Also, because there are six repeated notes in each group, she can keep playing 321 over and over again so the fingering is quick to learn. (Getting them even is the tough part!)
The reasons you can play quicker with three fingers than one are simple biomechanics: with three fingers, one finger can be on the way down while another is on the way up, and each muscle has three times as much time to recover before it needs to fire again as it would have when using one finger.
I might mention that I play this piece (maybe half as fast and with quite a few more wrong notes) myself, and there's no way I could begin to do it with using the same finger twice in a row on the repeated notes.