I'm going to guess here. SSRS needs additional components. .Net can run inside SQL Server, there are probably additional components there too.
In any event, installing SQL 2012 won't whack stuff so it isn't usable.
I have SQL 2012 installed in my laptop and haven't seen any issues.
>Here is what I have (see attached). I do have .NET Framework 4.0 installed so why SQL Server 2012 thinks I don't have installed (and VS Shell 2010) is beyond me. Moreover, I have found one vs_setup.msi on the CD and one in c:\Nadya\VS2010 Beta folder. They both don't work.
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer