When it comes to the title of this story, Bradbury sure had a lot of ideas to choose from. The whole thing takes place in the Hadley's house, so why not "Happylife Home"? Or it could have been called "The Nursery," since that's what this family is fighting over. But Bradbury opted for the much stranger "The Veldt."
Why? Well for one thing, it helps focus us on the world that the kids are imagining—a world full of death and lacking any adult supervision. (Like Vegas, only with fewer lions.)
In fact, when this story was first published, it was titled "The World the Children Made." This title would have worked well thematically, given that the focus here is on the children and their rather disturbing behavior, which is, of course, a result of their rather dangerous minds. This story is all about what the children made.
Except, here's the problem: that title tells us to focus on what the children make, but it doesn't actually tell us what they make. "The Veldt" does. It keeps our attention on this lions-run-amok imaginary world that is the product of the children's horrifying imaginations. It's about more than gadgetry and newfangled technology. At its heart, this is a story about some seriously nutso kids.