Sharepoint Integration & Navigation Links

I just noticed that the new protocol for accessing PerformancePoint doesn't work in a Sharepoint Navigation URL (fails validation)

The PerformancePoint Server protocol handler enables PerformancePoint Server users to open planning assignments through hyperlinks. This protocol handler is automatically installed on every client computer where the PerformancePoint Add-in for Excel is installed.
The PerformancePoint Server protocol handler is automatically registered when PerformancePoint Add-in for Excel is installed and appropriate registry keys are created.

PerformancePoint:http://server:46788&application=myapp&assignment=4119

One question I have is why didn't they just link to an Excel Worksheet with some parameters, or a web page that exports a worksheet that fires the PerformancePoint add-in, instead of adding the complexities of a protocol handler?

Here's more info on the protocol handler:

http://technet.microsoft.com/en-us/library/bb660547.aspx