Tickling as punishment is definitely a turn on for most of us because the concept of "control" is a major component of the tickling fetish. The idea of tickling as punishment, i.e., using tickling to disincentivize certain behavior, gives the 'ler not only physical control over the 'lee but also psychological control. That is why it is so intriguing to us.
I doubt this happens very much in real life though. I mean, what are some plausible scenarios that involve only adults? Female #1 tickling Female #2 as punishment for flirting with her boyfriend? A resentful stepmother finding some excuse to tickle punish her 18-year old stepdaughter? Those are fun ideas but have they ever actually happened? It might be fun to do a google search to try to find documented cases.
Another topic that might be fun to share stories on is the "dark side of tickling." I find that when I chat with other folks on this site and others in private, such as through the PM system, most folks have at least one story of when they saw tickling used to humiliate the lee, or out of jealousy, or just generally to make the lee uncomfortable or unhappy in some way. That is to say, the ler's intent was not to be fun or playful but to hurt the lee, not physically, but with the intent of causing the lee embarrassment, of hurting the lee's reputation, etc. Some of those stories can be very hot as well.