A handful of things can make or break a great off-road vehicle, but the two most important things are tires and shocks. Without a good set of tires, you're nowhere. You can't climb obstacles, you can't go fast, you can't make your way through streams or rivers or even light fire roads. You're up a creek.
But without shocks, and good ones at that, you're really screwed.
Shocks are the linchpin that holds the whole off-road vehicle together. Bumps loosen nuts and bolts and screws. You don't have enough articulation to even climb a mole hill. And you're spine becomes that damn thing's suspension. As someone who still aches from a long-since motorcycle crash, my spine's continued health remains important to me and my well-being, so I gotta have good shocks.