Yes I understand the scenario you described and I realize that computer people find things to argue about from all sides. I just think it needs to be put into perspective.
Yes it's true that if someone has a sniffer installed and is monitoring your network they may capture your password in clear text. They may also be a web developer and use that information to access your account and download your extensions. They may also cause the activations to exceed the limit. At which point someone is likely to notice.
You reset the activations and change your password. If anyone would be out anything, it would be WA, and they can change the serial numbers. Life goes on. You need to consider that not everyone keeps records of their accounts manually, and appreciate having an email with all the information they need. Sometimes convenience wins over security.
We have used one type of security for shopping mall networks for years without any problems. The networks for Nevada casinos use portable keys that change pass codes several times a second and are synchronized with a central server. One is obviously more secure, but each method fits the need.
The main reason you seem to be irritated was the result of the reuse of a password. If you had used a unique password, and were worried about it being compromised, it would be fixed by visiting your account and changing it. The emailing of login information is a pretty common practice. Some of the mailing lists I belong to, send that information out every month.
I'm sure you realize that neilo's armored trucks are a little extreme, and many people don't have secure email, so I think it's a risk worth taking. It would be a different story with your bank.
For one company, we actually improved security by reducing the measures they had deployed. They were changing the passwords so often that employees couldn't keep up and started writing them down. An overzealous IT manager thought it he was being pro-active and never took human behavior into account. Not only did eliminating the policy stop a serious flaw, it increased moral significantly by removing a constant irritant.
You might want to look into using something like RoboForm. That makes it a trivial matter to generate any kind of password you need, and keeps track of them for each site. That would increase security and convenience at the same time.