Hi bluethink,
I can't tell if you have a question about web based report designers or just making statements.
If you are looking for a more complex drag-drop web based report designer, then have a look at the BIRT Report Studio. I talked about it recently in my blog at
If Only Reports Could Build Themselves… » Blog - BIRT Exchange.
As for the data relationships, you are correct that the typical report consumer or business user does not understand, or even care about the relationships of the underlying table data. This is why the BIRT Report Studio can get its data from a metadata layer called Information Objects which allows you to predefine the relationships and then some built-in logic which trims the queries to only pull what the user has selected.
Use the same link above to build your own report on our demo server and then let me know if you have any questions.