SQL Server Management Studio not installed with Sql Server 2005 Installation

I came across this problem when trying to install Sql Server Management Studio and other client tools. Basically, for many different reasons, Management Studio and other client tools will not install after you've installed SQL Server 2005 server components. The error that is thrown is below -

Name: Microsoft SQL Server 2005 Tools Express EditionReason: Your upgrade is blocked. For more information about upgrade support, see the "Version and Edition Upgrades" and "Hardware and Software Requirements" topics in SQL Server 2005 Setup Help or SQL Server 2005 Books Online.
Build version check:
Your upgrade is blocked because the existing component is a later version than the version you are trying to upgrade to. To modify an existing SQL Server component, go to Add or Remove Programs in Control Panel, select the component you would like to modify, and then click Change/Remove.


A screen shot of this problem is here:



The problem here is basically that SQL Server 2005 installer seems to think that a higher version or something of SQL Server is already installed on this machine and therefore blocks the current installation by disabling the checkbox that could've made all our lives much easier.




As the obvious rectification step, I tried to find that missing prior installation of SQL Server but as expected, it was nowhere to be found and also for some reason this problem can't always be rectified by reinstalling SQL Server. So, we can't uninstall the previous version that SQL Server installer thinks is already there and we are stuck. So what gives? It turns out that we can set SKUUPGRADE to 1 while installing from the command prompt - E:\>setup.exe SKUUPGRADE=1 - This enables that silly checkbox to allow installation (or upgradation) of the client components. Below is how this command prompt looks on my system for reference -




Once you run the installer with SKUUPGRADE ON, you should be able to see the option to install SQL Server Management Studio in the installer. Below is a screen shot that shows how it looks now (please ignore the Integration Service thing as that's disabled in the picture for an entirely different reason) -




Now when you click Next, you should see the below -




Now click "Install" button and install the client components! But why is it so, how would a normal user know that he needs to do it via command prompt with some flag, why isn't that flag available as some advanced installation option in UI itself  and why doesn't the error message provide some info about this possible (and in many cases, only) solution? Well, I've to say that Microsoft and specifically whoever designed this Sql Server 2005 installed must be [...fill this one yourself...]