Drop2Open will reverse this default behavior. It will open the file in the program as in OSX dock when you dragging a file onto a pinned taskbar program.
That is, simply dragging and dropping will now open the file in the program, while Shift-Drag and Drop will pin the program to the jump list.
Drop2Open is a freeware AutoHotKey script for Windows 7. After installation, it will launches on start-up and runs in the system tray. It detects when you drag a file onto a docked program and proceeds to open it.
The program requires a little memory when running; it will only take up about 3MB of memory so speed should not be an issue. Download Drop2Open from programs home page.