If you aren't focusing on longtail keywords on your paid activity, here is further evidence that you might just be missing more than a little trick......it could in fact be the difference between success and failure.
If you are looking at it purely from an ROI point of view there are usually no downsides, they generally convert at a higher rate, have lower bid cost on PPC and therefore your Cost Per Acquisition will look even better.
Obviously managing a greater number of keywords increases time but once you have your sets tested and tweaked.
Bidding on long-tail keywords creates a better match between user intent, as expressed through the search query, and the landing page. Furthermore, bidding on specific long-tail keywords helps marketers avoid users who are less likely to buy and who would otherwise been have exposed to the ads via broad match. It also helps them focus the ad spend on the best potential customers. As a result, conversion rates and cost per acquisition are positively affected.