But there are workarounds.
You an 'drag' tabs to where you want them, or, if you keep an empty tab next to the open tab window, then you can drag the link to the open tab itself and it will open the link.
Not entirely suitable I know, but it may be useful.
Does anyone know if there is a way to tell IE8 not to move the position of tabs? I have to use it quite often for work but a lot of the time if I enter a new URL in a tab that is not to the left IE will automatically move it to the far right. It's not a big deal but just mildly annoying. I usually just grab it and move it back to where it was originally.