Understanding the balance of terms that might be a little more difficult due to competition, versus those terms that are a little more realistic, will help you maintain a similar balance that the mix of long-tail and head terms allows. Remember, the goal is to end up with a list of keywords that provide some quick wins but also helps you make progress toward bigger, more challenging SEO goals.
Google prefers to not share long tail searches in this tool – because the tool is designed for Google Adwords advertisers. If advertisers bid on those long tails – they would have less competition and therefore pay less for the Adword, and therefore Google would make less money e.g. bidding on the term weight loss for girls under 18 is cheaper than weight loss.
It would be great if you can provide comparative analysis of this tool with Google Keyword Planner. Since you’re using this tool so you can provide best comparison. One differentiation which I understood is that this tool works for yahoo and bing as well whereas Google keyword planner works only for Google but Google being a dominating search engine, gives the highest returns, so only this reason may not be enough to buy it.