Anger doesnt solve anything It just makes things worse. When you are angry at one thing you start looking for flaws in everything else. In turn you stop seeing clearly as nothing is how it "should be" when everything is as it was created. A user is a user, you just use what someone else creates, if you are not happy with it you find an addon, a plugin, or an alternative. While I have never used WLM, I have had bad experiences with Thunderbird. If your looking to send large emails it may not be the client rather the host. In all reality email is slow now we have file hosting sites such as Skydrive, dropbox, that let you store your files for free. These are faster, and typically more secure than a plain text email any 15 year old who can use Google can pick up.
Please do not think I am bashing you but rather giving you another perspective to look at your situation.
Thunderbird is o0pensource so maybe a lil Google work can get you a block list addon