The more obscure or least popular the show the better because it helps transport them to that time when they were still care-free children.
This is attitude is actually not strange but a very normal kind of behaviour, in fact just observe a group of friends who grew up during a particular era ? the 70's or the 80's for example ? and you will notice that their conversations would usually drift towards what they would usually watch on TV. We have practically grown up with the television blaring its programs in our households and as years progress, there are TV shows that we have come to associate with either a certain aspect of our life or particular point in our growing up years. It is an ubiquitous part of any household and it is also a regular source for free entertainment. We are a generation that has grown up with the television set as a constant companion of our lives.
Why would nostalgia be associated with TV themes anyway? It is simple, really. Choosing tv theme ringtones present a different side of a person's personality ? one that loves or is a fan of nostalgia. One of the more popular ringtone types that most mobile users prefer to use are ringtones based on TV themes.