Seal provides a package that is hard to come by these days. In an age where machines sing to our ears more than a human's vocal chords, it's easy to lose sight of what music really is about. It's not about "sessions" of instruments as much as solos of singers, at least in cases where these music sessions are not by a solo instrument (generally just a lot of pop, like Citizen Cope). Although I appreciate both to an appropriate degree, I find singers like Seal providing the music landscape with so much vigor and beauty that if you find these singers, you can get a musical experience that corresponds to what you could have found in other times, when music was of higher quality, like the crooner or synth pop or grunge, etc., eras.
Beyond that, Seal is also a good model. Most of today's singing celebrities are considerably unfavorable "role models" for people listening to them (bling-bling rappers, slutty women), and let's face it - everyone looks for inspiration from their music, and therefore, that inspiration also naturally arises from the singers themselves. Seeing that musicians have a special personal responsibility for their music, since their work can affect people so much (especially when their lyrics can match a random person's life troubles), it's important that such great artists like Seal have that accountability. Doubtlessly, Seal comes out to be a responsible family man, an introspective thinker, and a man with good character.
That's all I ask for from a person I draw inspiration from, and I'm glad I found Seal in this endless sea of "musicians" or "singers" that lacks the above credentials.