Provide better insights to know the product
Knowing other customers' shopping experiences helps potential buyers to recognize whether this product is what they need. When a consumer leaves a review for a product, he is helping others to understand what they may expect from the product, what are its pros and cons, and more.
Build trust with the customers
When a customer is browsing your listing to make a purchase, the first thing they do is to check the reviews. If the product has no reviews or only a few reviews, they usually assume that no one is buying the product. Having reviews for a product is a good way to build trust with your customers. Usually, people prefer products with more reviews.
Help sellers to improve the product
If a good number of customers point out that there are some problems with the product, the seller should take it seriously and find a way to rectify the issues with the product. Otherwise, sellers will lose current customers and potential customers.
It's important to follow Amazon's rules when asking for reviews. Amazon can not tolerate any customer reviews violations.
Keep the following don'ts in mind of requesting Amazon product reviews.
Don't review your own product or trash your competitors.
Don't incentivize reviews.
Don't isolate the buyers with positive experiences.
Don't try and divert sales to an external site.
Don't ask for a specific kind of review.
(Source: https://www.edesk.com/blog/requesting-amazon-product-reviews/)