I have a few "combo" name packages I'm looking at. I think if the search criteria change and start filtering extensions, regions and content then it will serve to hold multiple extensions.
Protecting brands, marketing efforts and against piracy is motivation to control multiple keyword domains as an internet company.
Marketing could dictate your presence in the .mobi arena as it grows in viable marketability.
As well as other reasons I think grouping or "combo" packaging ext is a plus.
IMHumbleO
namenut