Brand (or manufacturer) profiles enhance usability and also help with search engine optimisation. Many users like to shop by brand; having a feature which allows a user to go directly to a page dedicated to a brand (which displays all products by a selected brand) enables the user to find the product they are looking for faster. This helps to ease (and speed up) the shopping process and also increase conversions.
Brand profiles are good for search engine optimisation because the site has multiple brand sections. Each brand profile becomes an optimised page dedicated to the selected brand and its associated products.