According to a study by Searchmetrics, Schema markup shows up in more than a third of all Google’s search results. With this huge SERP preference for Schema, you’d think that sites would be flocking to implement Schema snippets wherever they could.
People are seeming to be slow on the uptake on Schema though but then it takes input, which in turn costs money to get put in place ...
Please me know if I need to add schema for products than I need to add in all products or any short-cut way for this so that it can effect on all the products because Upload schema for 15000 products is not an easy way so please suggest.
It's not an easy job but not a hard job either. You can hire a developer and as soon as they type few lines of hard-code magic, schema tags for all the product pages will be placed. You can learn more about implementing schema tags here: Micro Data, JSON-LD & Schema: Rich Snippets Guide. You can include the schema tags from ratings, reviews to votes etc through schema tags through that guide. Hope this helps!