If this was a conventional business, Microsoft for example, I would probably agree that more cooperation and tech sharing between the Xbox and Live divisions would be a good thing. Increase communication, reduce redundancies, all that good business stuff.
For some open source projects, like Gnome, I get the feeling the shaman is often strong than the salesman. Corporate help aside, the personal/emotional attachment of OSS contributors drives involvement in ways a big number next to market share percentage can't. But even steadfast contributors would like to see the product used, so Gnome and others aren't off the hook completely.
Should Gnome be more cooperative with 3rd party apps? Maybe. Personally, I'm thankful for the amount of quality OSS that let's a company, like Canonical, build on the shoulders of giants and offer a system better tailored for end users. That's where the request for cooperation is more realistic.
Still...
I haven't used Linux IM clients in a while but the Pidgin debacle made me wince a little.