While I agree that Apple seems to be suffering from internal management struggles right now (not that such a thing is exactly new to the company!) -- I'm not sure a lack of upgrading Siri is a definite indicator of bad decision-making on Apple's part?
Despite Cortana and other copy-cats coming along, people still think of Siri as THE virtual assistant, including the distinctive sound of her voice. If you're in a situation where you only have so much software development talent to go around and you have to prioritize projects -- the idea of funneling time and money into making Siri more intelligent isn't necessarily what needs to be at the top of Apple's list.
It seems to me that Siri is pretty extensible under its existing framework. I mean, any time Apple wants to give Siri more ability to answer back about something, it just needs to add the relevant queries to a database and feed it the data used to respond. That's all that's really necessary to keep Siri a relevant and useful tool.
Viv is interesting, in that it's trying to take things to the next level with ability to stack queries and figure out more about context of questions when incomplete information is given. But I see a problem with that. The more you try to fake true intelligence and ability to converse with a person, the more you broaden the expectations of the person interacting with the system. With Siri, I think people pretty quickly figure out where the boundaries are. (EG. Every time I do much beyond asking a specific question about one topic, Siri starts telling me it doesn't understand, or reverts to sending me off to web search page results. So I learn Siri is for basic, quick queries only.)
In that demo example of Viv, he asks about the weather near the Golden Gate Bridge without specifying where the bridge is. Viv is able to figure that out to give a useful response. Great - but I bet that only works because the Golden Gate Bridge is a significant enough landmark that someone thought to code in information about its location. That sets certain expectations. So when I ask about weather at the "family campground" (assuming it knows I mean the only campground in my small town), will it do the same thing?