Nowadays sharing isn't the only way to contribute to the todays world of gnutella with ultrapeers. I see three different groups

1. Users with slow connections
2. Users with broadband connections
3. Users with high speed connections (megabit symmetrical or more)

The first group has very limited amount of bandwidth. They should share only few files and open few upload slots. That will help them maintaining good upload success rate despite the poor connection speed.

Second group has two alternatives:

1. Become an ultrapeer and don't share files. By maintaining large amount of leaf and peer connections will help everyone. It is okay to not share, you help the network by supporting leaves. It is important to left your client on your computer all the time. It is also important to reserve enough bandwidth to your client.
2. Stay as leave and share plenty of files. You can reserve more of your upstream to uploads by staying as a leaf. You can serve fast uploads to people and you should have enough shared files to saturate your upload bandwidth.

Third group has enough bandwidth to share files and become an ultrapeer and serve leaves. You don't have to compromise anything.



So I think it is not bad if you don't share if you can run your client as ultrapeer.