I have been unable to find an option within Thunderbird or any existing Thunderbird add-on that changes this behaviour, so I have written my own addon / extension.

Above: Clicking the date column header sorts in ascending order (oldest messages first). You need to click it a second time to get descending order.
Introducing the NewFirst Add-on
This addon does one thing only. By default, all columns (including date) are sorted in ascending order when you click the column header.With the NewFirst add-on installed, the date column will sort in descending order on the first click, and back to ascending order on the second click.

Above: With the add-on installed, clicking the date column header sorts the messages in descending order (newest messages first).
Brutally simple, sure, but this has been bugging me for some time.
Download
Download newfirst.xpi here. Compatible with Mozilla Thunderbird 2.0.0.18 - 2.0.0.*Important notice: I'm having a few problems with the xpi uninstalling itself when restarting Thunderbird. I'm working on it, but it's not proving easy to fix. I'll update the page once I get it sorted soon.
Installation
- Download the newfirst.xpi and save to your local computer.
- Open Thunderbird, select Tools from the menu, then Add-ons.
- Click Install, then browse for newfirst.xpi where you previously saved the file.
- After installation, restart Thunderbird.
- Try clicking the column header for the Date column (pictured above). If messages are sorted newest at the top after the first click, it's working.
There are no configuration options for this add-on. To revert to Thunderbird's default behaviour, uninstall the add-on.









