Back when I was working on BUGS we grappled with several 'virtual reality' story ideas and none of them ever worked out. We finally concluded that they never would; an action show is about real perils, not perils that you know are merely perceived. When you send your characters into a virtual reality you're essentially asking your audience to empathise with someone watching a movie.
I know there are some people for whom it's all just movement on the screen and it amounts to the same thing, but let's leave those happy morons to their simple pleasures and continue.
If the dangers aren't real for the characters, they aren't real on any level at all. The only time I've ever seen it work is where a disparity or tension between the dream-world and reality is the point of the exercise, and not an inconvenient truth. For example, there's The Thirteenth Floor, based on Daniel Galouye's novel Counterfeit World; Avatar isn't part of this argument, as the characters project into a (to them) physical world, not a virtual one.
The usual element invoked to give weight to a virtual reality story is that creaky old trope of "If you die when you're in there, you die for real out here." There's no point asking why. The answer's only ever going to be some technobabble.