I'll get to the point quickly. The problem with (language learning) podcasts is quite simply that they are modelled on radio.
Podcasting started with a bunch of early technology adopters who wanted to play at being a DJ. They produced programs (semi-)regularly playing music, talking about minority interests etc. They built a successful little community, and everyone suddenly wanted to hang out with the cool kids.
The language profession has always looked for ways to employ new media to produce new ways of delivering classes, and suddenly they had something new. Or so they thought.
I'll indulge myself with a bit of repetition: the problem with (language learning) podcasts is quite simply that they are modelled on radio. Radio -- that's nothing new. Language learning hasn't been popular on the radio since people called it "the wireless". They found it didn't work very well, but moved onto TV. However, there haven't been many major TV language projects since the 80s (except in the field of English teaching). Again, it didn't really work.
Because radio and TV are effectively the same thing, under the hood.
They are casual media. You tune in, you tune out, as and when you like. Programs have to be clever to avoid this: soaps are popular with producers because they retain their audiences through extended story arcs. A more profound effect is that professional musicians are losing favour in TV prime-time to amateurs -- because a talent show has winners and losers, and with a knock-out format you come back to root for your favourite, even if you don't like the other guys.
Dedication to a single program, to tune in week after week, isn't easy, which is why most TV shows fail. Which shouldn't be a problem for a language course, because people doing it are going to dedicate the time to it, right?
But holding your viewers isn't worth anything if you can't pick up new ones. About 10 years ago there was a sci-fi series called Farscape. It was very well written, and as a book it would have been an outstanding success. But the problem was that it kept building on itself, so it was difficult for new viewers to understand, or for people to come back to viewing it after a break. Though the series had a strong following, the few viewers it did lose were never replaced, and it got cancelled before it reached the final series.
And this is the problem for the language program on TV or radio: by its very nature it cannot build an audience: you have to watch from the start.
So why is this a problem for podcasts? After all, we can download old podcasts -- we're not just restricted to this week's....
True, but once the program has been written as though it were a weekly radio program, there's a certain cognitive dissonance with playing catchup.
Every podcast has its jingles, it's little chatty banter, and all too often they end with "see you next week" or something of that ilk. I for one find it unpleasant to listen to that when I'm doing an episode every day. In fact, I find a lot of the banter irritating if I'm only listening to one episode a week. The banter is part of the radio style, it's not alway there for pedagogical reasons.
So I have to ask myself: why write a language course modelled on radio programs, when instead you could write a language course modelled on language courses? It's not like there's a dearth of materials out there to model yourself on: Linguaphone, Pimsleur, Michel Thomas and several other successful products exist on the market, and among them, some have survived a notably long time, unlike the short-lived fad for radio programmes.
Many of these don't have jingles (unlike the irritating audio accompanying many school textbooks), none of them are interspersed with chatty banter and very few have inane encouragement (phrases like "keep it up, you're really doing well" in a patronising voice really wind me up). Lessons usually start with a lesson number and a title, and nothing else. You may be given advice on the recommended frequency of use, but it's not rammed down your throat by someone gushing "see you next week! Cheeeeriooooo!"
So please, people; write language lessons, not radio programs