[Z]

It's only retrospectively become an "insult" to refer to them as a boy band... it's just an observation, and clearly one that a lot of other people have noticed too. It's the whole cult of personality built around them as individuals, more than anything. If we were to compare them to more contemporary examples:

The Beatles = McFly - known for making their own music with crossover appeal to the pop market, legions of fans who have stuck by them for years, and each member individually has achieved things outside of the band to build names for themselves as individuals as well as a group. They're a boy band, but in a different sense to what the term is usually applied to.

The Jackson 5 = Pussycat Dolls. Obviously a bit different (opposite genders; being a singing band rather than singers/dancers; being good rather than being Nicole Scherzinger) but the comparison is obvious. One breakout star fronting a concept with very little emphasis on the rest of the group members, but they all play their part and bring something new to the table as a unit. For the Jackson 5, it was that they were a black family band who all sang, played instruments, and introduced choreography into their performances; with Michael being the lead singer and obvious solo star. The Pussycat Dolls brought the idea of a burlesque group turned pop act to pop music. Some of the members weren't singers, they were dancers, but they were marketed as a group with a powerhouse singer who could also dance really well too. Nicole, like Michael, was obviously a solo star in the making but needed that initial push to break into the public conscience.

The Monkees = S Club 7. The TV shows introduced a fever pitch of fandom and the music came along with it. Entirely engineered by a producer in order to fill a gap in the market, both groups became internationally famous thanks to their television programs and musical careers and both are still very much remembered for what they achieved even years after they ceased to exist as entities.