Do most streamers care about much more than showing game footage? I doubt most think of themselves as journalists at all.
They care about hits and views, above all else. That's how they make money.
Anything they can do to attract more viewers and subscribers means more money.
That can mean anything - in the case of most CoD youtubers I've seen, it means pretty vapid videos churned out at an amazing pace. The better ones are interesting, informative, funny, or some mix of the above.
Streaming is a bit different - seeing/hearing people play games can be more interesting, or a lot worse, depending on the person (realtime raging!).
There are some people are are in a weird place as far as 'journalism' goes. They do what amounts to reporting news. Some do what amounts to reviews, or previews.
Honestly its a new medium, and sort of a wild frontier. The popularity of the bigger channels exploded over the last few years, and they've created thousands of imitators.
The imitators are actually pretty fucking annoying, a very regular thing that youtube people do is take someone ELSES video, post it up, and slap their commentary on top of it. This is especially hilarious when this is a partner posting up, say, an official trailer, and they're making money off this. But sometimes it's not even an official PR piece (who I'm sure are happy to be getting even more exposure, because it'll get MORE hits on that page than the original), it's another youtubers video!
The end result though, is that searching for something on youtube often winds up giving you a shitload of copycat videos that are just someone reposting someone elses video over and over again, all with slightly different headers.
Seriously, go try searching for 'BO2 guns' or something, you'll get a shitload of people talking over footage of BO2 trailers, gamescom footage, or even BO/MW3 gameplay.
Note that developers and publishers are getting in on this as well, there are livestreams direct from devs (sometimes with amusing results). I would not be even the least bit surprised to see some of these people hired directly by companies to act as their 'face' for the internet.