For example I sell stuff on Etsy, I have about 50~ 5 star reviews if I get one 1 star review my average is now 4.92 which is still 5 stars. So it's really not that big of a deal, if I had say a 4.8 with 40,000 ratings a series of a 100 in a row 1 star reviews will do nothing to my score of 4.8.
If I for say had five 5 star reviews and got one 1 star review, my average is 4.3 which will show a 4.5 (or a 4 star depending on how they round) at the star rating.
If you are new you have zero room to get a bad review, even if you fix it. There are version reviews, etc that can fix that but, largely you're done.
I really have no idea of how to redo this, but I don't think people should be giving a 5 star review with a comment. There should be considerations, reviews after a certain time should expire, you should be able to mark reviews as fixed, etc.
I believe the current system is completely broken and needs to be adjusted a bit more then hiring some additional staff to read reviews.