Default action for Windows Explorer Pin under Taskbar is set to Libraries, which is kind of unusable. If I want to start Computer, either I have to Go to Start Menu and select Computer, or I have to go to Desktop, and launch Computer from there in Windows 7. But in Windows 8, since there is no Start Menu, I've to go to Desktop, and launch Computer from there.
With this small process, you can change your Windows Explorer Pin/Icon under Taskbar to Computer, Control Panel, Documents, C: Drive, D: Drive or whatever you want.
How to Do -
Step 1. Right Click on Windows Explorer Pin, then Right Click on Windows Explorer in Jump List, and go to Properties from there.
Step 2. Under Target field, it will look like this. You have to change this Address to appropriate address.
If you want it to change the icon to C: Drive, then type here c:\
for D: Drive, type d:\
or browse to any any address which you want the default action for this Taskbar Icon.
But make sure, it's an address, if you put Computer, it will not work, because it required a target path, which should be a valid address, not title.
Use following command as Target to select various Targets
Computer
%windir%\explorer.exe /n,::{20D04FE0-3AEA-1069-A2D8-08002B30309D}
or
%windir%\explorer.exe shell:MyComputerFolder
Documents
%windir%\explorer.exe /n,::{450D8FBA-AD25-11D0-98A8-0800361B1103}
Downloads
%UserProfile%\Downloads
Recycle Bin
%windir%\explorer.exe /n,::{645FF040-5081-101B-9F08-00AA002F954E}
Network Neighborhood
%windir%\explorer.exe /n,::{208D2C60-3AEA-1069-A2D7-08002B30309D}
Default Web Browser
%windir%\explorer.exe /n,::{871C5380-42A0-1069-A2EA-08002B30309D}
Control Panel
%windir%\explorer.exe /n,::{20D04FE0-3AEA-1069-A2D8-08002B30309D}\::{21EC2020-3AEA-1069-A2DD-08002B30309D}
Will update more, if I found more commands, or you can make your request in Comments Section.
