The 2005 Doraemon anime was trying to survive in a world that didn't seem to need it anymore. Just last year, in 2004, a push began to include content that pushed the boundaries of acceptable content in anime, such as Elfen Lied and Nin-Nin Shinobuden. The phenomena known as "Otaku O'Clock" wasn't new, but it certainly started to get a lot more mileage around that time.
An outbreak of sexual content started to flood the markets, all of which used plenty of female nudity to entice 18-year-old male otaku with plenty of their parents' money to spend, and not an inkling of common sense to spend it on something to better their life. This was the era of the rise of fanservice OVAs, of DVD bonus content, of fanservice posters, figurines, and more content for perverts to satisfy their worst desires. Gradually and gradually, sexual female nudity became the only kind of female nudity allowed, and none of it was to be placed anywhere near the kids, even innocently.
In particular, one anime in 2004 started to change the game on how content involving child characters was used; Magical Girl Lyrical Nanoha. Based on an alternate story to a hentai game, Nanoha starred Nanoha Takamachi as a magical girl, with a frilly dress and a magic wand. But this was no ordinary magical girl; Nanoha was aimed at an older male demographic, with lots of epic battles, a lesbian romance, and fanservice... and all of it involved elementary school-aged girls. Nanoha quickly became known for sexual loli fanservice, to the point where a movie remake actually upped the service.
All of this meant that nudity was slowly becoming the realm where only adults played, but the real damage would be done a year after the Water Play episode of Doraemon with a pair of particularly evil anime. Before that, however, Doraemon would have to deal with its darkest moment yet, one which would ultimately serve the perfect reflection of the industry...