The biggest problem about the patcher is that the devs seem to not understand they are crippling it themselves. I think someone thought it would be smart to offload some bandwidth usage to the users, but what they didn't think of is that once someone finishes downloading, s/he drops out of the swarm.
Torrents live from big swarms, so giving people the option to seed after finishing downloading would increase speeds for everyone.
Another problem is that on ADSL (~90% of people in Europe), using unlimited upload speeds as it does now, clogs the whole line, because there is no bandwidth left for sending ACK-packets - download speed falls. Simply doing a speed test and setting the upload @70% of the total would be completely sufficient. Just don't forget to save the test results and not waste our time on every boot.
Then there are people who can not use torrent because of ISP blocking or throttling P2P traffic. If you go as far as to forbid hosting patches ourselves, (which is pretty stupid imho, since it costs you nothing) then at least host the files yourself.
Of course, people still continue to host those files anyway... for those who find them it's a way out, but many don't even know manual patching is possible. Those players are essentially lost as customers, SE.
Yes, there is another thread about this issue, but it's already derailed
edit: adding other points mentioned in the thread (to summarize)
Allowing other torrent clients into the official swarm would be great too. SE seems to forget that there is no way to smuggle modified data into a torrent swarm. So there is definitely no harm in allowing us to use our own torrent clients. (Cutriss)
Introducing incremental updates. There is no reason having to re-download all the files if only a few of them were actually modified (Renshi)
edit2: another point:
You could fix 2 problems by making the patcher a hybrid; meaning providing the patch via http and torrent. That's how Blizzard does it and it works quite fine. That way people who can't use torrents will be able to at least leech via http, albeit slower, and there will be less load on your servers.
Additionally, you should give us an option to seed after finishing the download, reducing the load on your servers even further.
edit3: Something else that should be in a patcher is a possibility to run a filecheck and fix any damaged files. The implementation is simple, you host a checksum file on your server that lists all the correct md5 hashes for the latest version of each file. This file is downloaded by the client when the user clicks "filecheck" and then feed this list to your md5 checker. If a hash mismatch occurs, the patcher downloads this file from the server and runs the check again.