The system tray works as intended (i.e. by design). Single click toggles visibility. If it was minimized when you hid it, it will still be minimized when you unhide it. This is intentional. You might want it to always be minimized, but be able to toggle it's visibility on and off to make it dissapear and reappear on the taskbar. I personally like to leave it on the taskbar (minimized but visible) because then I can easily see the state, and the last command.
The one enhancement that I could think of adding that would fit with my intended design, would be that if you unhide it when it is not minimized, it should also bring it to the front in case it is hiding behind other windows.
The other option would be to add a bunch of right click options, but I find this to be generally rather cumbersome for the user. Ther are a few on there already, but I for one never use them.