Immediately after you submit your suggestion, the site populates a list of reasons they may not be able to add the title. They specifically list Game of Thrones as an example of something they can't add to the library because they've clearly had way too many subscribers ask for that one. The reasons you aren't getting your wish include that a show may be exclusive to another company (a la Game of Thrones), the "streaming rights are not available," and "other factors" like "popularity, cost, or seasonal or localized availability."
They've also clearly had some repeat customers because they specifically note that you don't have to re-submit your ideas. If you've let them know you can't live without Big Man Japan, they passive-aggressively suggest you "sit back and relax." "We've received your feedback and there's nothing more for you to do."