I don't think theres any particular link between tickling and anime other than alot of people into tickling are also teens, young adults, or adults and are into anime as well, which is now a mainstream media and artform.
While it is true the japanese have many fetishes and perversions and they don't hide them in their anime, I think the casual observer will only see the tickling stick out if they themselves have a liking for it.
Otherwise the casual observer will just be like "LOL, that was funny, wtf" or whatever. They don't put as much time or attention into it as you or the creators might.
It is, and perhaps will always be, a private joke, that is of course if the animators put the tickling in there because they like it the same way you do. We shouldn't assume that however. It could, afterall, just be there to pass the time to the next scene and the people making this series don't have the fetish but just the general liking for it, enough to use it as filler or a plot device of some sort.
In that regard its less and less premeditated, and it shows because of the time, or lack therefore, on the scene and the detail involved. This is why less fetishists are likely to enjoy these types of scenes or never hear about them at all, because they didn't necessarily deliver on the level you would have liked.
Of course, also add to the fact that most tickling scenes in a mainstream series are 5-7 seconds long, on average. Film-wise, thats alot of screen time, but to a viewer it goes by like it was nothing.