I would be happy if there was a switch, but you do realize you just need to right click once and it's gone, right?
I use the thumb joystick on my G13 for movement, and because not everything fits on the pad, there are things I have to do with my mouse while I'm moving. Having your character suddenly start following your mouse around at top speed can mean the difference between success and failure in pvp, and in certain situations, such as the trapped path to the puzzle board quest, it can mean the difference between life and death. And it can all happen before you have a chance to right click.
I'm getting used to it, but it is a problem, and it should be fixed. But at this point it has been months since the last patch that actually addressed any of the problems with the Enhanced Client, and I am getting a bit discouraged. The fact that more than half the dev team was apparently laid off leads me to believe that we aren't going to see a patch for some time to come. There are some serious (in game terms) problems with the client, and this is only one of them.
It's too bad. The game really felt like it was undergoing a true Renaissance with the new client, and the new expansion with wonderful additions like imbuing, but it really feels like EA has thrown a spanner in the works with the layoffs, and I am beginning to seriously wonder what their long term plans for UO really are.