There's way too many podcasts. There's too many conferences, too many businesses, too many blogs. Everyone wants to start their own thing.
I do it too. You're reading my blog right now. Making things on your own is awesome, and it's never been easier.
So does that mean you shouldn't start the podcast (or blog, or business) you've been dreaming about?
Of course not. It just means that if you want people to listen to it, you have be better than most podcasts. That could mean higher production value, better preparation, a topic no one is talking about, etc.
We may not need "just" another podcast, but regardless of how saturated a market may be, there's always value in making something great.