Here's the problem: you want to go on a trip by train, and it's 500 miles away. What do you do when your battery dies? Proprietary batteries are for chumps.
Touche! You are indeed correct, proprietary batteries are for chumps. Why couldn't Apple or Creative just put a replaceable battery on these things at the expense of just a small amount of space increase in the package size? That way, you could carry an extra with you if on a long train trip. In any case, I think my Zen would make it through a 500 mile train trip.
Problem number 2: what happens if you happen to drop your precious zen? Hmm...can you say "bad sectors"?
Good point. Although I have dropped my Zen twice onto pavement from hip height and the vinyl case protected it from visible damage and the hard drive still appears to work Ok. But you are correct, there is a pretty good risk here (although replacing the hard drive on a Zen is no big deal -- many ppl have upgraded to 60GB disks). I would contend that the MD players are relatively fragile as well if dropped from 5 or 6 feet.
Problem number 3: what happens if you are only wearing very light clothing (shorts and a tshirt) and you want to listen to your music on the go? The minidisc player would have fit conveniently into the smallest of pockets. Mr. Zen won't fit? Awww...that's a shame.
Well, I wouldn't put a Zen or iPod in a shirt pocket because of comfort concerns, but I did attach a cell-phone-style belt clip to my Zen case and this works great -- hangs on my hip just like a cell phone. As long as I wear a belt, this is no problem.
Problem number 4: you make under $20,000/year and you've got bills to pay. Your budget is only $150. Again, what a shame, you can't afford the zen.
Well, yeah, that's problematic. Although a friend of mine told me his high-end MD player cost almost $300!
Give it a couple of years and the hard drive based players are going to kick some serious @$$. The problem with them right now is that the hard drive constantly spins (correct me if i'm wrong here). The MD players achieve such a long battery life by only spinning the disc for a few seconds every minute or so. I'm sure that they could adopt this to the hard drive players, but then once you start skipping songs you're in trouble.
Well, no, the hard drive only spins for a few seconds to load the tracks into the buffer (Zen has 16MB, iPod 32MB) just like the MD players. No skipping. Why the battery life is not longer on HD players, I don't know.
Maybe in 2 years your arguements will be able to convince me, but as it stands now I'm very happy with my minidisc player.
I admit that HD players are no panacea for the moment. I can't wait what is available 3 years from now, though.