I am positive that i saw change in rating when user changed his 5 star rating to 1 star, but ok.
Maybe it was because 5 star rating was removed and it has nothing to do with 1 star rating.
So you don't think that simple like/recommend button would be better (easier for users)?
EDIT: Actually 1 star ratings are counted.
On second asset i have 4 ratings
3 = 5 star ratings
1 = 1 star rating (from the same user i mentioned above)
and on page i see 4.0 rating.
What exactly you mean with this "one solitary" 1-star rating?