The people who enjoy the torrents are the people who download them in the first place. And believe me, they do appreciate it, even if it goes unspoken.
To put it in other terms: if 50 members and 50 non-members download your torrent and only 5 members click Thanks, you get your figure of 5% feedback. If you block the 50 non-members from downloading, that number rises to 10%. But your overall swarm has dropped by half.
As for getting direct feedback, it will always be disproportionate simply because that's how all torrents are. "Thanks" is not built into bittorrent, so it's strictly optional. If you don't like that, you'll just have to pick a different P2P protocol, or find some other way to encourage/force people to give you thanks before they get access to your .torrent files.
Frankly, the number of peers in the swarm is the best indication of how much your efforts are appreciated. If you have thousands of peers, you know that a lot of people both on the forum and off the forum are thankful for your efforts. If you only get a handful of peers, the files themselves simply aren't popular and no amount of Thanks will change that.
If you want to put it into perspective, you can simply stop uploading anything and see if members begin to ask what happened and ask for you to come back. If you've been contributing a lot, people will undoubtedly notice the change; but they will learn to move on, with or without you.
