There has been excessive concern regarding search engines and how they index and rank contents. In earlier times this worked since the algorithms were is early stage of evolution but with constant addition and changes this is not the case anymore.
In the contemporary times it has become mandatory to add meaningful content relevant to the topic or product in case of e-commerce sites. It is not necessary to add content just for the sake of it. But yes meaningful content is desirable that which is readable and useful. The placement of content is of importance as well. Too much content above the fold will hide or reduce visual element this is not good for user attraction. It is better to add a paragraph followed by an image or a video.
In case of product description the read more element is very useful. Since adding too many lines will hide the product image away and detract visitor, it is better to add just two lines followed by read more for those interested in reading the description further. The format in case of product/item description may include reviews, ratings, specification, about and more. More angles to image are usually added so fit in that aspect as well. Creating product pages is a challenging job, hastily done it will detract the user in one go. In case of many similar products it is tempting repeat description which is a dead giveaway. Hire a content writer and unique descriptions.
Remember when it comes to online success usability wins hands down. Better user experience is the right formula for success as for search engine they have become more sophisticated and can decipher your naturally written content to index and rank properly.