We do get into a hair splitting thing here, but a Cruiser is based on a Cruiser frame and a Cruiser as a total package has a certain engineering ethic to its design that includes overbuilding and doing just about everything possible to ensure reliability, durability, and longevity. Over time they have evolved but share a lot of mechanical features, of which the FJ Cruiser shares few. Real Cruisers are also built at the Araco assembly plant, although we have evidence that 100 series Cruisers are no longer built there.
The FJ Cruiser is a marketing exercise more than anything else. It is a Tacoma mechanically, at least as it has been presented by Toyota to date. Nothing wrong with Taco's - best mid sized pickup in the world besides the Land Cruiser pickups that are available only in non-USA markets. But a Tacoma is not a Land Cruiser - it's not meant to be one, which is fine, it is what it is. Toyota took the Tacoma chassis and built onto it this goofy body that borrows some of its look from older Cruisers.
If it was a Land Cruiser then Toyota would call it that.