I think it would be really good to analyze trends by filtering, or at least, sorting the Etsy product results by listings' age. It would be a great way to see what the recent products are like and which do people like more: view more, buy more, review more...etc as well as how the demand changed on a certain product (or more) over a selected period of time (eg. Between last year and this year there were less sales in this niche and more on this niche for the same product. Or this demographic gravitated more towards this product in the last month instead of the most popular product of last year,...etc) which would help analysing the market as a whole, and have better predictions for the coming holiday, season, quarter...etc insha'allah.