Given enough light, why prefer high ISO instead of slower shutter or larger aperture?

Most photos on camera review sites and camera manufacturer sites are taken in auto or program modes, using camera chosen exposure settings, default image settings and jpgs without any post processing.  This is done to show what the camera can do if you know nothing about photography and simply point and shoot.  So I would not read into these photos any kind of 'decision' by the photographer.

Different manufacturers have different priorities for what the camera chooses, and within the same manufacturer, there can be very different priorities for different cameras or lenses (probably at least partly due to outsourcing).

In general (and this is certainly very general, there are as many exceptions as there are adherents), the more 'consumer' the lens or camera, the more the camera will choose to play it safe --- small aperture, high shutter speed, higher ISO.  I suppose that is to mimic the huge depth of field that the user has presumably come from with a point and shoot camera.  Indeed, the most common complaint when someone buys an ILC for the first time is that the newer, more expensive gear is not providing the same level of 'sharpness' that the old p&s did.  Sometimes, however, the camera has overriding quirks, such as never moving past base ISO no matter how low the shutter speed gets unless you switch to S mode.

I frequently shoot in P mode and initially was very irritated by the stupid settings chosen by m4/3 cameras (such as f16 rather than raising the shutter speed).  Especially since P mode on regular 4/3 was very reliable and 'smart'.  That seems to be tied into the earlier lenses, as P mode works fairly well for any lens I have purchased in the last 2 years -- but I still can't use P mode for earlier lenses.  I think both Panasonic and Olympus went into m4/3 thinking this was a system for folks moving up from p&s, so those decisions are rational even if highly obnoxious to me.