The evolution of computer VFX into a seamless post asset.
Premium Beat has list here highlighting the importance of modern VFX in storytelling with a collection of super impressive VFX reels for films such as "Nightcrawler", "Zodiac" and "Children of Men". I think the best sign that indicates VFX have crossed a significant threshold in terms of a post asset is that they can be used to augment a scene to help push a narrative forward as opposed to being the reason a movie exists (although the latter still happens; I'm looking at you "San Andreas" and "Pixels").
The examples listed on Premium Beat really show the power of VFX to streamline a frame, keep the viewer focused on the main message and provide some added production value in the face of a tight shooting schedule or bootstrapped budget. Yes, "fix it on set" is always, always, always, always, always, always best but more tools are never a bad thing and technology helping to tell better stories opens up more avenues for making cool stuff.
Commercial production is no exception and I look forward to seeing what kind of madness we can pump out in the next year.
Counterpoint: Here are some ways the VFX should definitely not be used.