Great. You could try starting a thread here:
http://discussions.apple.com/category.jspa?categoryID=149
If you post a link, maybe someone else will want to back you up.
Unfortunately, Jim, Apple representatives don't monitor the Apple Discussion Forums very well unless one of the moderators notices a post and forwards it up the chain (rather than deletes it). Those moderators aren't Apple employees by-and-large, they are mostly forum regulars that have been elevated to super-user status. They ain't J River!
The most effective ways to send Apple feedback are:
1. If you have an Apple Hardware product (like an iPod) call AppleCare. I have done this and explained that I'd like to be able to use my third party applications to directly sync my media on my iPhone. This gets passed on. Apple listens to people who actually call AppleCare. Remember how they mentioned the AppleCare statistics at the AntennaGate presser? It may help to ask for a supervisor before you explain yourself.
2. Larry posted a great set of links to the different Feedback forms Apple provides for their products. If you'd rather write than call, this would be the best means by far.
iPod Classic: http://www.apple.com/feedback/ipod.html
iPod Touch: http://www.apple.com/feedback/ipodtouch.html
iPhone: http://www.apple.com/feedback/iphone.html
The main page for selecting another product (like iPod Nano or Shuffle) is: http://www.apple.com/feedback/
3. Another option that has actually been shown to work over and over again: Write a letter to Steve Jobs. It can be an email, but actual physical letters really can work as well. This is true especially if you send the letter via a package carrying service (FedEx or UPS) rather than USPS. Even I get tons of piddly promotional junk and vendor "hello letters" in my regular mailbox at work, but if I get a FedEx, it comes to me directly from our receiving department and I have to sign for it. I open those myself.
Another REALLY effective thing to do is to CC second-tier executives in your message (both physical ones and emailed correspondence). While Steve Jobs gets a TON of email, and all of his email goes through the Executive Customer Service department, if you also send a copy of your letter to Bertrand Serlet (Senior VP of Software Engineering) or Scott Forstall (senior VP of iOS Software), you might actually get their eyes on the letter. This means the issue could end up being discussed at their next meeting, which is exactly what you want.
Steve Jobs' email address: sjobs@apple.com
Other @apple.com email addresses seem to follow the same pattern, but executives may have "secret" internal addresses.
Corporate mailing address:
1 Infinite Loop
Cupertino, CA 95014
4. Lastly, apparently contacting the Executive Customer Support team directly can be very effective.
The Consumerist has posted this strategy:
1) Call Apple Corporate: 408-996-1010
2) Ask the operator for Gene (like denim) Teluse, VP of Customer Care. She is Apple's highest ranking customer service agent, and she reports directly to Steve Jobs.
3) Leave a nice message, include any Apple Case/Repair numbers you might have, or your machine's serial number, and a callback number.
4) Wait ~24 business hours for one of Ms. Teluse's minions to call.
5) Calmly explain your story, and what you want Apple to do.
It is very important to remember if you do this, that you aren't calling to berate Apple and tell them how you think they are doing something wrong or with a poor strategy. They won't listen to any of that. What you want to do is call them and explain this: "I'm a customer. I have an iProduct X. I like it, but it isn't currently meeting my needs because I am unable to sync my media to it using J River Media Center instead of iTunes. I need the third-party application instead of iTunes because it provides X" (and pick some feature that iTunes doesn't, like maybe FLAC support, or audiophile quality playback, or whatever). The point is, that you want to make it about YOU AS A
CUSTOMER, not about THEM AS A COMPANY. Make it a customer service issue, and they will respond to it as such. Make it about their corporate philosophy, and they'll ignore you as a fanboy or crackpot.