Sometimes I'll get a question like "Why would I use Reporting Services when I can use Excel?" or "Why does Microsoft have so many tools for building reports?" The underlying assumption behind these questsions is that a limited number of applications should be are able to work with data. IMHO, I think that working with data is something that should be included in every application, not just limited to "BI tools".
I look at interacting with data as a capability similar to formatting text or spell checking. No one asks "Why do I need to format text in PowerPoint when I have Word?" or "Who would need a spell checker in OneNote?". Applications can share a common set of capabilities but work in very different ways to achieve different results. Can you build a presentation in Word? Sure, but it's not optimal. Could you use PowerPoint to make a network diagram? Sure, but once again, it's not optimal. Anyone who has used Report Designer or Report Builder know that they feel different from Excel and make certain types of outputs easy to do (say, repeating groups of forms). At the same time, if someone feels comfortable with a working with a spreadsheet, they shouldn't feel compelled to use another tool just because they want to add data to it.
What should be common is how people work with data and what services they get around that data. Having every application work with data in a different way is like having every application with it's own way to edit text. In this area, we have a lot of work to do. If we can unify around a common set of experiences with data, I expect very soon that these features will show up everywhere.