I am not embarrased to play Pokemon. Why? Ratings are created so that people under a certain age can be protected from playing it. Unless it's a restricted rating, like in Aussie Land it's MA15+(Mature Audience Only), it's not demanding that you much be between certain ages to play it.
It seems to be a unilateral cultural problem that puts the 'taboo' on older people, 13+, playing Pokemon or 'Children's Games' in general. The notion that because the fanbase cannot grow with the franchise, and boy howdy, has Pokemon grown sence G1, is ignorance.
It is the exact same stigma that gets people, such as myself, comments on their sexuality because of what they enjoy. But by this logic, lots of kids enjoy sports, so is sport juvinille? Yeah, by that logic it is. Is it? No, it's quite barbaric in some circumstances to the degree no child would play it in the same way. Same goes for 'kids' games. A child would not get the same level of enjoyment. Same argument goes for toy collecting.