Jermaine never really caught on, except in the R&B market. A lot of people expect a Jackson to dance, which is part of the reason Janet caught on. Jermaine is more of a musician than an entertainer like Mike, Janet, or Marlon. Entertainer type acts in general are more popular today than just a singer or musician. But let's face it, Mike (or Janet) will draw a bigger audience than the others, unfortunately. Talent in itself sells no tickets, which is why a Soulja Boy or a Britney Spears will sell more tickets than a Jill Scott, a Esperanza Spalding, or a Raul Midon.
There was 2300 Jackson St, which Sony did little promotion on. Jermaine has over 10 solo albums and produced and did A&R duties at Motown. Jackie has 2. Randy started a band called The Gypsies and put out a record. Marlon had a solo. Even Tito recorded an instrumental album at Motown that was never released.