Corey Deitz captures what makes podcasting so appealing in a post at the Yahoo! Podcasting Group:

"The reason podcasting is so attractive is because it empowers anyone
with the smallest of means to share a passion with the whole world.

In my opinion, the most successful podcasts will be the ones that
provide something not already being offered. So, why would
potential listeners - many already disenchanted with the standard
commercial Radio offerings - want to subscribe to a podcast that
duplicates what's already there.

For the same reason Satellite Radio is finding its audience, so will
podcasts. You love wine? There's a podcast about it. You love
travel? Carpentry? Insect Life? Stamp collecting? Someone is going
to want to share that passion. Talking costs you nothing. Sharing
your own music costs you nothing. Interviews cost you nothing.
Advice costs you nothing. Using any audio in the public domain costs
you nothing.

The real subjects NOT being addressed on Radio, public or otherwise,
that people want to hear and learn more about are most likely not
necessarily music-based or at least don't have to use copyrighted
music to garner an audience.

Yes, it poses a problem for podcasters who want to have a weekly
show highlighting their favorite metal band's music - but - if
that's truly your passion, then you will have to be willing to go
along with the current copyright law when and as it's enforced or
operate as a renegade and hope you don't get sued.

What excites me the most about podcasting is the potential for
variety as never experienced before. This is podcasting's forte and
should be exploited to its fullest.

But, hey: that's just my opinion."

Well said, Corey.