Not all filler episodes are as pointless as they seem. Their primary function is to help pace the show properly, so it doesn't get ahead of itself. This is most readily evident in the long string of filler episodes that occured in the first year of the show, between the Sekichiku City and Guren Island gym battles. After that sixth badge, the anime producers realized that the show was a runaway hit, and they were going to be around for a good long while. Thus, they slowed down the pacing in order to not rush to the end too quickly. Furthermore, there are many filler episodes that allow the writers to stretch out and try new characters, revive old characters, or simply focus on the development of one of the main characters. When you watch the show and view it as a continuing soap opera-esque serial, then fillers can get annoying, but if you view it as simply an anime based on a video game, the impact of fillers is altered greatly.