As a retailer with over 20,000 products, we often have multiple products defined by a range. For example...the 'BOSS Katana Range' has 10 unique products within it.
It would be awesome if there was a filter to aggregate reviews for these 10 products and generate a 'product range' review widget. i.e. The BOSS Katana Range has a score of 4.9/5 stars so that we could use this on range landing pages and when promoting ranges to users who may not know which exact model they're looking for yet. There are loads of instances where a user may be interested in a range/product line before researching the models within it.
This is also prevalent when ranges update their product line!